Pulse eddy current scanning and positioning method and device for 304 steel plate zero-reinforcement welding seam under insulating layer

Abstract

The invention provides a pulsed eddy current scanning and positioning method and device for a 304 steel plate zero-reinforcement welding seam under an insulating layer. The method comprises the following steps: determining the direction of a welding seam on a 304 steel plate welding part according to a design drawing; determining a detection point by taking the base metal specification thickness as a step length in a direction perpendicular to the weld seam trend direction; a pulse eddy current testing (PECT) signal S (i, t) of the first detection point is obtained, and i = 1; taking an undetected adjacent point of the first detection point as a second detection point; acquiring a PECT signal S (i + 1, t) of the second detection point; calculating PECT differential signals DiffS (i, t) = S (i, t)-S (i + 1, t) of adjacent detection points; performing fitting on the DiffS (i, t) by using a 6-order sine function # imgabs0 #; when bnlt; 0, determining that a weld seam is below a detection point corresponding to the S (i, t); when bngt; if so, determining that the weld seam is below the detection point corresponding to the S (i + 1, t). By means of the pulsed eddy current scanning and positioning method and device for the 304 steel plate zero-reinforcement welding seam under the insulating layer, welding seam positioning can be accurately achieved.

Description

Technical Field

[0001] The invention relates to the field of pulsed eddy current detection, and in particular to a pulsed eddy current scanning and positioning method and device for a zero-residual height weld of a 304 steel plate under an insulating layer. Background Art

[0002] Welded parts composed of 304 stainless steel plates are widely used in petrochemical and offshore platforms because of their good corrosion resistance and mechanical properties. In order to reduce stress concentration and facilitate corrosion protection, the weld excess height of welded parts is often polished to zero. In order to protect the surface or maintain temperature, the surface of 304 stainless steel plates on most key devices is covered with insulating layers such as paint, rock wool or polyurethane. The weld is the weakest part of the weld and is the focus of regular inspection. However, at the inspection site, based on the design drawings and experience, only the direction of the weld can be determined, but it is difficult to determine the position of the weld. The insulating layer has to be removed over a large area. After the weld position is determined and the inspection is carried out, the insulating layer is restored, which is time-consuming and laborious. If the position of the zero excess height weld of the 304 stainless steel plate can be determined without removing the insulating layer, the area of ​​insulation layer removal and restoration can be reduced, thereby improving the weld inspection efficiency and reducing the inspection cost.

[0003] Pulse eddy current detection technology has the ability to penetrate the insulating layer to locate the weld. Li Jicheng, Zuo Jiaqi, et al. ([1] Li Jicheng, Cui Daguang, Li Huan, et al. Research on weld positioning technology for pressure pipelines with coating layers [J]. China Special Equipment Safety, 2018, 34(11): 28-30. [2] Zuo Jiaqi, Li Jicheng. Research on weld positioning of pipelines with coating layers based on pulse eddy current technology [J]. Nondestructive Testing, 2019, 43(04): 10-12.) Using non-zero weld height will lead to a difference in thickness and parent material. , which leads to the pulse eddy current detection signal mean square deviation (RMSD) value at the weld being different from that of the parent material, and the positioning of the Q235 pipe girth weld with covering layer is realized. However, for non-ferromagnetic materials such as 304 stainless steel, the difference in weld material and stress relative to the parent material is mainly reflected in the difference in conductivity in pulse eddy current detection, unlike ferromagnetic materials such as Q235, which will also be reflected in magnetic permeability. In addition, for zero-residual height welds, because the thickness at the weld is consistent with that of the parent material, the positioning of the weld cannot be achieved by detecting thickness changes.

[0004] Therefore, with the support of the National Natural Science Foundation Youth Project "Research on the Mechanism and Method of Pulse Eddy Current Detection of Local Defects of Non-Ferromagnetic Metal Components with Covering Layer" (62003056), technical personnel in this field provide a pulse eddy current scanning and positioning method and device for the zero-residual height weld of 304 stainless steel plate under the insulating layer to solve the above-mentioned technical problems. Summary of the invention

[0005] The present invention provides a pulse eddy current scanning and positioning method for a zero-residue weld of a 304 steel plate under an insulating layer, which solves the problem that it is difficult to directly observe the position of the weld in a zero-residue state after the weld with an insulating layer is ground flat.

[0006] In order to solve the above technical problems, the present invention provides a pulse eddy current scanning and positioning method for zero-residual height weld of 304 steel plate under an insulating layer, comprising the following steps:

[0007] S1. Determine the direction of the weld on the 304 steel plate weldment according to the design drawings;

[0008] S11. Collect the design drawings of 304 steel plate welded parts and carefully check the weld-related information marked on the drawings, including the approximate position, shape and direction of the weld;

[0009] S12. Combined with the previous method of processing similar 304 steel plate welded parts, considering the deviation of weld direction that may occur in the actual welding process, the accurate direction of the weld on the welded part is comprehensively determined;

[0010] S2, perpendicular to the direction of the weld, determine the inspection point with the thickness of the parent material as the step length;

[0011] S21, after the direction of the weld is determined, find a direction perpendicular to the direction of the weld;

[0012] S22. Check the specifications of 304 steel plate base material and obtain its thickness information;

[0013] S3, obtaining a pulsed eddy current test (PECT) signal S (i, t) of the first test point, where i = 1;

[0014] S31, placing a probe of a pulsed eddy current testing (PECT) device on the first testing point;

[0015] S32, start the pulsed eddy current testing (PECT) equipment, and set appropriate testing parameters, such as testing frequency and testing time, where the time parameter is denoted as t;

[0016] S33, the equipment starts to work, and obtains the pulsed eddy current detection signal at the first detection point, which is recorded as S(1, t);

[0017] S4, taking the undetected adjacent point of the first detection point as the second detection point;

[0018] S41, observing the adjacent points around the first detection point that have not been detected;

[0019] S42, selecting the next adjacent point of the first detection point as the second detection point according to a preset detection order;

[0020] S5, obtaining the PECT signal S(i+1,t) of the second detection point;

[0021] S51, moving the probe of the PECT device to the second detection point;

[0022] S52, maintaining the same detection parameters as in S3;

[0023] S53, obtaining a pulsed eddy current detection signal of the second detection point. Since i=1, the signal obtained at this time is recorded as S(2,t);

[0024] S6, calculate the adjacent detection point PECT differential signal DiffS(i,t)=S(i,t)-S(i+1,t);

[0025] S7, use the 6th order sine function Fit DiffS(i,t) and get a n , b n 、c n , where n = 1, 2, ..., 6;

[0026] S8. Determine whether b is satisfied n <0? Where n=1,2,……,6. If yes, it is determined that the detection point corresponding to S(i,t) is below the weld and the process ends. If no, it proceeds to S9.

[0027] S9, determine whether b is satisfied n >0? Where n=1,2,……,6. If yes, it is determined that the detection point corresponding to S(i+1,t) is below the weld and the process ends. If no, it proceeds to S10.

[0028] S10, take the second detection point as the first detection point, i=i+1, and enter S4;

[0029] S101, re-mark the original second detection point as the first detection point, and the value of i changes from 1 to 2;

[0030] S102, return to S4, repeat the subsequent detection, calculation and judgment steps until the position of the entire weld is determined.

[0031] A pulse eddy current scanning and positioning device for zero-residue height welds of 304 steel plates under an insulating layer comprises: a base, a power supply is installed on one side of the base surface, and a drive module is symmetrically installed on the surface of the base and located on one side of the power supply;

[0032] A ball screw slide, wherein the number of the ball screw slides is two, and the two ball screw slides are symmetrically mounted on the surface of the base;

[0033] Stepper motor, the number of the stepper motors is two, and the two stepper motors are respectively installed at one end of the two ball screw slides;

[0034] A connecting plate is installed between the two ball screw slides, and a pulse eddy current probe is installed on one side of the connecting plate.

[0035] Preferably, directional wheels are installed at the four corners of the bottom of the base.

[0036] Preferably, the directional wheel is provided with an encoder which can output the moving distance of the directional wheel.

[0037] Preferably, the stepper motor and the ball screw slide are used to drive the pulsed eddy current probe to move.

[0038] Preferably, a protection component is provided between the connecting plate and the pulsed eddy current probe, and the protection component comprises a protection cover, and mounting blocks are connected to both sides of the surface of the protection cover.

[0039] Preferably, external thread blocks are provided inside the two mounting blocks, and one end of the external thread blocks is connected to the connecting plate.

[0040] Preferably, a threaded sleeve is threadedly connected to the surface of the external thread block.

[0041] Preferably, the protective cover is used to protect the pulsed eddy current probe.

[0042] Preferably, the inner wall of the protective cover is sequentially connected with a plurality of protective rings from top to bottom.

[0043] Compared with the related art, the pulse eddy current scanning and positioning method for zero-residual height weld of 304 steel plate under insulation layer provided by the present invention has the following beneficial effects:

[0044] The pulse eddy current scanning and positioning method and device for zero-residual height weld of 304 steel plate under the insulating layer provided by the present invention show, through the difference curve results in the lift-off experiment, that for the welded parts with a thickness of 6-12mm under the insulating layer, the weld positioning can be realized relatively accurately;

[0045] The pulse eddy current scanning and positioning method for the zero-residue height weld of 304 steel plate under the insulating layer provided by the present invention can realize the positioning of the zero-residue height weld of 304 steel plate without removing the insulating layer, laying a foundation for subsequent further detection of weld defects, with high efficiency and environmental friendliness.

[0046] The pulse eddy current scanning and positioning device for zero-residue height weld of 304 steel plate under insulating layer provided by the present invention has small volume, flexible and movable x and z axes, high flexibility and adjustability, and is convenient for detection and operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 A schematic structural diagram of a first embodiment of a pulse eddy current scanning and positioning method and device for zero-residual height welds of 304 steel plates under an insulating layer provided by the present invention;

[0048] Figure 2 It is the 6th order sinusoidal function fitting diagram of base material and base material area;

[0049] Figure 3 It is the 6th order sinusoidal function fitting diagram of weld and base material area;

[0050] Figure 4 The differential curve diagram after the receiving coil voltage data at 50mm and 40mm, 40mm and 30mm, 30mm and 20mm, and 10mm and the weld are derived and differentially processed;

[0051] Figure 5 The plane reference map corresponding to the six position points with a detection step of 10 mm;

[0052] Figure 6 This is a three-dimensional view of the pulse eddy current scanning and positioning device for the zero-residual height weld of 304 steel plate under the insulation layer;

[0053] Figure 7 It is an isometric structural schematic diagram of a pulse eddy current scanning and positioning device for zero-residual height welds of 304 steel plates under an insulating layer;

[0054] Figure 8 This is an exploded view of the pulse eddy current scanning and positioning device for the zero-residue high weld of 304 steel plate under the insulation layer;

[0055] Fig. 9 A schematic structural diagram of a second embodiment of a pulse eddy current scanning and positioning method and device for a zero-residual height weld of a 304 steel plate under an insulating layer provided by the present invention;

[0056] Fig.10 for Fig. 9 A partial enlarged view of the middle A part;

[0057] Fig.11 The plane reference diagram corresponding to the five position points of the 8mm thick welded part inspection;

[0058] Fig.12 The plane reference diagram corresponding to the five position points detected for a 6mm thick weldment.

[0059] Fig.13 The plane reference diagram corresponding to the five position points detected for a 12mm thick weldment.

[0060] Numbers in the figure: 1. Drive module; 2. Stepper motor; 3. Ball screw slide; 4. Power supply; 5. Connecting plate; 6. Pulse eddy current probe; 7. Orienting wheel; 8. Base; 9. Protection component; 91. Protective cover; 92. Mounting block; 93. External thread block; 94. Threaded sleeve; 10. Protective ring. DETAILED DESCRIPTION

[0061] The present invention will be further described below in conjunction with the accompanying drawings and implementation modes.

[0062] First embodiment

[0063] Please refer to Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 , Figure 8 , Fig.11 , Fig.12 , Fig.13 ,in, Figure 1 A schematic structural diagram of a first embodiment of a pulse eddy current scanning and positioning method for a zero-residual height weld of a 304 steel plate under an insulating layer provided by the present invention; Figure 2 It is the 6th order sinusoidal function fitting diagram of base material and base material area; Figure 3 It is the 6th order sinusoidal function fitting diagram of weld and base material area; Figure 4 The differential curve diagram after the receiving coil voltage data at 50mm and 40mm, 40mm and 30mm, 30mm and 20mm, and 10mm and the weld are derived and differentially processed; Figure 5 The plane reference map corresponding to the six position points with a detection step of 10 mm; Figure 6 This is a three-dimensional view of the pulse eddy current scanning and positioning device for the zero-residual height weld of 304 steel plate under the insulation layer; Figure 7 It is an isometric structural schematic diagram of a pulse eddy current scanning and positioning device for zero-residual height welds of 304 steel plates under an insulating layer; Figure 8 This is an exploded view of the pulse eddy current scanning and positioning device for the zero-residue high weld of 304 steel plate under the insulation layer; Fig.11 The plane reference diagram corresponding to the five position points of the 8mm thick welded part inspection; Fig.12 The plane reference diagram corresponding to the five position points of the 6mm thick welded part inspection; Fig.13 The plane reference diagram corresponding to the five position points of the 12mm thick welded part inspection. The pulse eddy current scanning and positioning method of the zero-residual height weld of 304 steel plate under the insulation layer includes the following steps:

[0064] S1. Determine the direction of the weld on the 304 steel plate weldment according to the design drawings;

[0065] S11. Collect the design drawings of 304 steel plate welded parts and carefully check the weld-related information marked on the drawings, including the approximate position, shape and direction of the weld;

[0066] S12. Combined with the previous method of processing similar 304 steel plate welded parts, considering the deviation of weld direction that may occur in the actual welding process, the accurate direction of the weld on the welded part is comprehensively determined;

[0067] S2, perpendicular to the direction of the weld, determine the inspection point with the thickness of the parent material as the step length;

[0068] S21, after the direction of the weld is determined, find a direction perpendicular to the direction of the weld;

[0069] S22. Check the specifications of 304 steel plate base material and obtain its thickness information;

[0070] S3, obtaining a pulsed eddy current test (PECT) signal S (i, t) of the first test point, where i = 1;

[0071] S31, placing a probe of a pulsed eddy current testing (PECT) device on the first testing point;

[0072] S32, start the pulsed eddy current testing (PECT) equipment, and set appropriate testing parameters, such as testing frequency and testing time, where the time parameter is denoted as t;

[0073] S33, the equipment starts to work, and obtains the pulsed eddy current detection signal at the first detection point, which is recorded as S(1,t);

[0074] S4, taking the undetected adjacent point of the first detection point as the second detection point;

[0075] S41, observing the adjacent points around the first detection point that have not been detected;

[0076] S42, selecting the next adjacent point of the first detection point as the second detection point according to a preset detection order;

[0077] S5, obtaining the PECT signal S(i+1,t) of the second detection point;

[0078] S51, moving the probe of the PECT device to the second detection point;

[0079] S52, maintaining the same detection parameters as in S3;

[0080] S53, obtaining a pulsed eddy current detection signal of the second detection point. Since i=1, the signal obtained at this time is recorded as S(2,t);

[0081] S6, calculate the adjacent detection point PECT differential signal DiffS(i,t)=S(i,t)-S(i+1,t);

[0082] S7, use the 6th order sine function Fit DiffS(i,t) and get a n , b n 、c n , where n = 1, 2, ..., 6;

[0083] S8. Determine whether b is satisfied n <0? Where n=1,2,……,6. If yes, it is determined that the area below the detection point corresponding to S(i,t) is a weld, and the process ends. If no, it proceeds to S9.

[0084] S9, determine whether b is satisfied n >0? Where n=1,2,……,6. If yes, it is determined that the detection point corresponding to S(i+1,t) is below the weld and the process ends. If no, it proceeds to S10.

[0085] S10, take the second detection point as the first detection point, i=i+1, and enter S4;

[0086] S101, re-mark the original second detection point as the first detection point, and the value of i changes from 1 to 2;

[0087] S102, return to S4, repeat the subsequent detection, calculation and judgment steps until the position of the entire weld is determined. The weld is located at a lifting height of 8mm and a detection step of 10mm for a 6mm thick weld.

[0088] The PEC differential signals at 50mm and 40mm are processed differentially, and the results are as follows: Figure 4 The curve drawn in solid line is shown.

[0089] The PEC differential signals at 40mm and 30mm are processed differentially, such as Figure 4 It can be seen that there is a great similarity between the first two curves, with only slight differences in values.

[0090] The PEC differential signals at 30mm and 20mm are processed differentially, and the results are as follows: Figure 4 The curves drawn by the midpoint line are shown. It can be seen that there is a great similarity between the first three curves, with only slight differences in values. There are also similarities in direction, but the differences are not obvious enough.

[0091] The PEC differential signals at 20mm and 10mm are processed differentially, and the results are as follows: Figure 4As shown by the curve drawn by the thin dotted line.

[0092] The PEC differential signal at 10mm and the midpoint is processed differentially, and the result is as follows Figure 4 The curve drawn by the circle “o” in the middle shows that the difference between the differential curve and other curves can be clearly observed.

[0093] Fitting with a 6th order sine function Fit DiffS(i,t) and get a n , b n 、c n , where n = 1, 2, 3, 4, 5, 6;

[0094] When b n >0, where n=1,2,3,4,5,6, the detection position corresponding to S(i+1,t) is determined to be the weld; otherwise, the detection position corresponding to S(i+1,t) is determined to be the base material.

[0095] Table 1: Values ​​of parameters in the 6th order sine function fitting

[0096]

[0097] Four experiments were conducted for comparison in the lift-off experiment (keeping the voltage and other parameters unchanged). In the experiment, the probe lift-off height was 5 mm. Data was collected at five points for each group of experiments. The reference views of the collection points of 12 mm, 10 mm, 8 mm, and 6 mm thick welded parts are shown in the figure below. Fig.13 , Figure 5 , Fig.11 , Fig.12 shown.

[0098] In the weld positioning experiment, one piece of 304 stainless steel weldment with diameters of 12 mm, 10 mm, 8 mm, and 6 mm was used.

[0099] A 3mm thick organic glass plate was used as the insulating layer, and the weld positioning experiment under the insulating layer was carried out.

[0100] Experiment 1: Lift-off test on a 12mm thick weldment

[0101] Table 2: Values ​​of parameters in the 6th order sine function fitting

[0102]

[0103] Experiment 2: A 10mm thick welded part was used as the test object, and a 10mm thick 304 stainless steel welded part was used as the experimental object for lift-off test.

[0104] Table 3: Values ​​of parameters in the 6th order sine function fitting

[0105]

[0106] Experiment 3: Take 8mm thick welded parts as the test object, and take 8mm thick 304 stainless steel welded parts as the experimental object for lift-off test.

[0107] Table 4: Values ​​of parameters in the 6th order sine function fitting

[0108]

[0109] Experiment 4: A 6mm thick welded part was used as the test object, and a 6mm thick 304 stainless steel welded part was used as the experimental object for lift-off test.

[0110] Table 5: Parameter values ​​for the 6th order sine function fit

[0111]

[0112] Weld positioning experiments were carried out on 304 stainless steel weldments of various thicknesses.

[0113] To verify the applicability of the experiment, this experiment was conducted at a lifting height of 0mm and 10mm based on a lifting height of 5mm for a welded part with a thickness of 8mm under the paint layer (keeping the thickness of the welded part unchanged).

[0114] A 3mm thick organic glass plate was used as the insulating layer, and the weld positioning experiment under the insulating layer was carried out.

[0115] Experiment 5: Take the 8mm thick welded parts as the test object, and perform a lift-off test on the 10mm thick 304 stainless steel welded parts at a lift-off height of 0mm.

[0116] Table 6: Values ​​of parameters in the 6th order sine function fitting

[0117]

[0118] Experiment 6: Take 8mm thick welded parts as the test object, and perform lift-off test on 10mm thick 304 stainless steel welded parts at a lift-off height of 10mm.

[0119] Table 7: Values ​​of parameters in the 6th order sine function fit

[0120]

[0121] The positioning test results of 6-10mm thick 304 stainless steel welded parts and the positioning test of 0-10mm lift-off height for 8mm thick 304 stainless steel welded parts show that there is a certain difference between the sine function parameter values ​​fitted between the parent material and the weld and the sine function parameter values ​​fitted between the parent material and the parent material. By comparing all the parameter values, it is found that the 6th order sine function fitting parameter b between the parent material and the weld is n >0, and the sixth-order sinusoidal function between the base material and the base material fits each parameter b n Some values ​​are greater than zero and some are less than zero, and there is no positive or negative pattern overall.

[0122] The results of the sinusoidal function parameters in the lift-off experiment show that the weld positioning can be achieved relatively accurately for welds with a thickness of 6-12 mm under a 3 mm thick insulating layer and a lift-off height of 0-10 mm.

[0123] A pulse eddy current scanning and positioning device for zero-residue height weld of 304 steel plate under an insulating layer comprises: a base 8, a power supply 4 is installed on one side of the surface of the base 8, and a driving module 1 is symmetrically installed on the surface of the base 8 and located on one side of the power supply 4;

[0124] A ball screw slide 3, wherein the number of the ball screw slides 3 is two, and the two ball screw slides 3 are symmetrically mounted on the surface of the base 8;

[0125] Stepper motor 2, the number of the stepper motor 2 is two, and the two stepper motors 2 are respectively installed with one end of the two ball screw slides 3;

[0126] A connecting plate 5 is installed between the two ball screw slides 3 , and a pulse eddy current probe 6 is installed on one side of the connecting plate 5 .

[0127] The four corners of the bottom of the base 8 are all equipped with directional wheels 7 .

[0128] The directional wheel 7 is provided with an encoder, which can output the moving distance of the directional wheel.

[0129] The stepper motor 2 and the ball screw slide 3 are used to drive the pulsed eddy current probe 6 to move.

[0130] Scanning device: The device adopts a gantry design, mainly composed of a set of power supply and drive module, two sets of stepper motor ball screw slide module, a crossbeam, a set of pulse eddy current probe and its fixture, a bottom plate, and four directional wheels 7. Among them, the power supply 4 and the drive module 1, the stepper motor 2, and the ball screw slide 3 are installed on the bottom plate, and the directional wheels 7 are installed at the four corners below the bottom plate;

[0131] The stepper motor ball screw slide module is mainly composed of a stepper motor, a ball screw and a slide, which can convert the rotation of the stepper motor into the linear movement of the slide (Y direction).

[0132] Both ends of the beam are installed on the slides of two sets of stepper motor ball screw slide modules, and can be moved along the Y direction by the two sets of stepper motor ball screw slide modules;

[0133] The pulsed eddy current probe and its fixture are composed of a pulsed eddy current probe and a fixture, wherein the fixture is composed of a long strip fixture plate and an L-shaped fixture head. The pulsed eddy current probe is fixed below the horizontal plane of the L-shaped fixture head by screws. Four bolts are passed through the vertical plane of the L-shaped fixture head and the long strip through-hole grooves on both sides of the long strip fixture plate. By loosening and tightening the bolts, the L-shaped fixture head can be moved up and down, thereby driving the pulsed eddy current probe to move up and down.

[0134] A rectangular hole is machined in the middle of the bottom plate so that the pulsed eddy current probe and its fixture will not hit the bottom plate when moving in the X and Z directions;

[0135] The moving direction of the directional wheel is the X direction. The directional wheel is equipped with an encoder which can output the moving distance of the directional wheel.

[0136] The positioning device is characterized in that the host is mainly composed of a computer, a signal generating module, a power amplifying module, a signal amplifying module, and a data collecting module;

[0137] Scanning device control software and pulse eddy current detection software are running on the computer. Through this software, on the one hand, motion instructions can be issued to the power supply and drive module to control the movement of the stepper motor ball screw slide module and drive the pulse eddy current probe to move along the X direction; on the other hand, a waveform generation instruction can be issued to the signal generation module, and the generated waveform is amplified by the power amplifier module and loaded into the pulse eddy current probe. The pulse eddy current detection signal obtained by the pulse eddy current probe is amplified by the signal amplifier module and converted into a digital signal by the data acquisition module, and analyzed according to the positioning method of claim 1; in addition, the moving distance of the pulse eddy current probe can be obtained by obtaining the moving distance of the directional wheel and the moving distance of the slide.

[0138] Compared with the related art, the pulse eddy current scanning and positioning device for zero-residual height weld of 304 steel plate under insulation layer provided by the present invention has the following beneficial effects:

[0139] The present invention provides a pulse eddy current scanning and positioning method for zero-residual height weld of 304 steel plate under an insulating layer, and the sine function parameter b in the lift-off experiment is used to determine the position of the weld. n The results show that for welds with a thickness of 6-12 mm under a 3 mm thick insulation layer with a lift-off height of 0-10 mm, the weld positioning can be achieved relatively accurately.

[0140] Second embodiment

[0141] Please refer to Fig. 9 and Fig.10 Based on the pulse eddy current scanning and positioning device for zero excess height weld of 304 steel plate under insulation layer provided by the first embodiment of the present application, the second embodiment of the present application proposes another pulse eddy current scanning and positioning device for zero excess height weld of 304 steel plate under insulation layer. The second embodiment is only a preferred mode of the first embodiment, and the implementation of the second embodiment will not affect the independent implementation of the first embodiment.

[0142] Specifically, the difference of the pulse eddy current scanning and positioning device for zero-residue height welds of 304 steel plates under the insulating layer provided in the second embodiment of the present application is that, in the pulse eddy current scanning and positioning device for zero-residue height welds of 304 steel plates under the insulating layer, a protective component 9 is arranged between the connecting plate 5 and the pulse eddy current probe 6, and the protective component 9 includes a protective cover 91, and mounting blocks 92 are connected to both sides of the surface of the protective cover 91.

[0143] External thread blocks 93 are disposed inside the two mounting blocks 92 , and one end of the external thread block 93 is connected to the connecting plate 5 .

[0144] The two external thread blocks 93 are symmetrically connected to the left and right sides of the bottom of the connecting plate 5 . The protective cover 91 is sleeved on the surface of the pulse eddy current probe 6 . The protective cover 91 is mesh-shaped.

[0145] The surface of the external thread block 93 is threadedly connected with a thread sleeve 94 .

[0146] The protective cover 91 is used to protect the pulse eddy current probe 6 .

[0147] The inner wall of the protective cover 91 is sequentially connected with a plurality of protective rings 10 from top to bottom.

[0148] The working principle of the pulse eddy current scanning and positioning device for zero-residual height weld of 304 steel plate under the insulating layer provided by the present invention is as follows:

[0149] When in use, when protecting the pulse eddy current probe 6, first, the protective cover 91 with the mounting block 92 is put on the surface of the pulse eddy current probe 6, and at the same time, the mounting blocks 92 on both sides of the surface of the protective cover 91 are put on the surface of the external threaded blocks 93 on both sides of the bottom of the connecting plate 5, and then the threaded sleeve 94 is used to threadably connect with the external threaded block 93.

[0150] Compared with the related art, the pulse eddy current scanning and positioning method and device for zero-residual height weld of 304 steel plate under insulation layer provided by the present invention has the following beneficial effects:

[0151] The present invention provides a pulse eddy current scanning and positioning method and device for a zero-residual height weld of a 304 steel plate under an insulating layer. A protective component 9 and a plurality of protective rings 10 are arranged between a connecting plate 5 and a pulse eddy current probe 6 to protect the pulse eddy current probe 6 exposed to the outside.

[0152] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A pulse eddy current scanning and positioning method for zero-residual height welds of 304 steel plates under an insulating layer, characterized in that: The following steps are involved: S1. Determine the direction of the weld on the 304 steel plate weldment according to the design drawings; S11. Collect the design drawings of 304 steel plate welded parts, carefully check the weld-related information marked on the drawings, including the approximate position, shape and direction of the weld, and check the specifications of the 304 steel plate parent material to obtain its thickness information; S12. Combined with the previous method of processing similar 304 steel plate welded parts, considering the deviation of weld direction that may occur in the actual welding process, the accurate direction of the weld on the welded part is comprehensively determined; S2, perpendicular to the direction of the weld, determine the inspection point with the thickness of the parent material as the step length; S21, after the direction of the weld is determined, find a direction perpendicular to the direction of the weld; S3, obtaining a pulsed eddy current test (PECT) signal S (i, t) of the first test point, where i = 1; S31, placing a probe of a pulsed eddy current testing (PECT) device on the first testing point; S32, start the pulsed eddy current testing (PECT) equipment, and set appropriate testing parameters, such as testing frequency and testing time, where the time parameter is denoted as t; S33, the equipment starts to work, and obtains the pulsed eddy current detection signal at the first detection point, which is recorded as S(1,t); S4, taking the undetected adjacent point of the first detection point as the second detection point; S41, observing the adjacent points around the first detection point that have not been detected; S42, selecting the next adjacent point of the first detection point as the second detection point according to a preset detection order; S5, obtaining the PECT signal S(i+1,t) of the second detection point; S51, moving the probe of the PECT device to the second detection point; S52, maintaining the same detection parameters as in S3; S53, obtaining a pulsed eddy current detection signal of the second detection point. Since i=1, the signal obtained at this time is recorded as S(2,t); S6, calculate the adjacent detection point PECT differential signal DiffS(i,t)=S(i,t)-S(i+1,t); S7, use the 6th order sine function Fit DiffS(i,t) and get a n , b n 、c n , where n = 1, 2, ..., 6; S8. Determine whether b is satisfied n <0? Where n=1,2,……,6. If yes, it is determined that the detection point corresponding to S(i,t) is below the weld and the process ends. If no, it proceeds to S9. S9, determine whether b is satisfied n >0? Where n=1,2,……,6. If yes, it is determined that the detection point corresponding to S(i+1,t) is below the weld and the process ends. If no, it proceeds to S10. S10, take the second detection point as the first detection point, i=i+1, and enter S4; S101, re-mark the original second detection point as the first detection point, and the value of i changes from 1 to 2; S102, return to S4, repeat the subsequent detection, calculation and judgment steps until the position of the entire weld is determined.

2. Pulse eddy current scanning and positioning device for zero-residue weld of 304 steel plate under insulation layer, characterized in that: include: A base, a power supply is installed on one side of the base surface, and a driving module is symmetrically installed on the surface of the base and located on one side of the power supply; A ball screw slide, wherein the number of the ball screw slides is two, and the two ball screw slides are symmetrically mounted on the surface of the base; Stepper motor, the number of the stepper motors is two, and the two stepper motors are respectively installed at one end of the two ball screw slides; A connecting plate is installed between the two ball screw slides, and a pulse eddy current probe is installed on one side of the connecting plate.

3. The pulse eddy current scanning and positioning device for zero-residual height weld of 304 steel plate under insulation layer according to claim 2 is characterized in that: Four corners of the bottom of the base are all equipped with directional wheels.

4. The pulse eddy current scanning and positioning device for zero-residual height weld of 304 steel plate under insulation layer according to claim 3 is characterized in that: The directional wheel is provided with an encoder which can output the moving distance of the directional wheel.

5. The pulse eddy current scanning and positioning device for zero-residual height weld of 304 steel plate under insulation layer according to claim 2 is characterized in that: The stepper motor and the ball screw slide are used to drive the pulsed eddy current probe to move.

6. The pulse eddy current scanning and positioning device for zero-residual height weld of 304 steel plate under insulation layer according to claim 2 is characterized in that: A protection component is arranged between the connecting plate and the pulsed eddy current probe, and the protection component comprises a protection cover, and mounting blocks are connected to both sides of the surface of the protection cover.

7. The pulse eddy current scanning and positioning device for zero-residual height weld of 304 steel plate under insulation layer according to claim 6 is characterized in that: External thread blocks are arranged inside the two installation blocks, and one end of the external thread blocks is connected to the connecting plate.

8. The pulse eddy current scanning and positioning device for zero-residual height weld of 304 steel plate under insulation layer according to claim 7, characterized in that: The surface of the external thread block is threadedly connected with a thread sleeve.

9. The pulse eddy current scanning and positioning device for zero-residual height weld of 304 steel plate under insulation layer according to claim 6, characterized in that: The protective cover is used for protecting the pulse eddy current probe.

10. The pulse eddy current scanning and positioning device for zero-residual height weld of 304 steel plate under insulation layer according to claim 6, characterized in that: The inner wall of the protective cover is sequentially connected with a plurality of protective rings from top to bottom.

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