阅读说明：本技术 一种基于铁磁性板的缺陷检测方法 (Defect detection method based on ferromagnetic plate ) 是由 康宜华 唐健 于 2021-08-09 设计创作，主要内容包括：本发明属于电磁无损检测相关技术领域,其公开了一种基于铁磁性板的缺陷检测方法,所述检测方法包括以下步骤：(1)将磁传感器固定在铁磁性板上,所述铁磁性板开设有通槽,所述通槽沿所述铁磁性板的厚度方向贯穿所述铁磁性板,且所述通槽贯穿所述铁磁性板被所述磁传感器所覆盖的区域；(2)在磁化场中,所述磁传感器与所述铁磁性板对磁化后的待测工件进行缺陷扫查；其中,所述通槽在所述磁化场的作用下产生的漏磁场与待测工件上缺陷产生的漏磁场相互磁化及相互加强。本发明避免了抖动,增强了磁传感器的耐磨性,另一方面增强了漏磁检测信号,提高了漏磁检测灵敏度。(The invention belongs to the relevant technical field of electromagnetic nondestructive testing, and discloses a defect detection method based on a ferromagnetic plate, which comprises the following steps: (1) fixing a magnetic sensor on a ferromagnetic plate, wherein the ferromagnetic plate is provided with a through groove, the through groove penetrates through the ferromagnetic plate along the thickness direction of the ferromagnetic plate, and the through groove penetrates through the area of the ferromagnetic plate covered by the magnetic sensor; (2) in a magnetization field, the magnetic sensor and the ferromagnetic plate scan the magnetized workpiece to be detected for defects; and the through groove magnetizes and strengthens the leakage magnetic field generated by the defect on the workpiece to be detected and the leakage magnetic field generated by the defect on the workpiece to be detected mutually under the action of the magnetization field. The invention avoids shaking, enhances the wear resistance of the magnetic sensor, enhances the magnetic leakage detection signal and improves the magnetic leakage detection sensitivity.)

1. A defect detection method based on a ferromagnetic plate is characterized by comprising the following steps:

(1) fixing a magnetic sensor on a ferromagnetic plate, wherein the ferromagnetic plate is provided with a through groove, the through groove penetrates through the ferromagnetic plate along the thickness direction of the ferromagnetic plate, and the through groove penetrates through the area of the ferromagnetic plate covered by the magnetic sensor;

(2) in a magnetization field, the magnetic sensor and the ferromagnetic plate scan the magnetized workpiece to be detected for defects; and the through groove magnetizes and strengthens the leakage magnetic field generated by the defect on the workpiece to be detected and the leakage magnetic field generated by the defect on the workpiece to be detected mutually under the action of the magnetization field.

2. The defect detection method based on a ferromagnetic slab as set forth in claim 1, wherein: the magnetic sensor and the surface of the ferromagnetic plate, which is attached to the workpiece to be detected, move to scan the defect of the workpiece to be detected.

3. The defect detection method based on a ferromagnetic slab as set forth in claim 2, wherein: the distance of the magnetic sensor from the surface of the workpiece to be measured is constant.

4. The defect detection method based on a ferromagnetic slab as set forth in claim 2, wherein: the lift-off value of the magnetic sensor is the thickness value of the ferromagnetic plate.

5. A defect detection method based on a ferromagnetic slab as claimed in any of claims 1 to 4, characterized in that: an electrified coil or a magnetizer is adopted to form a magnetization field, and the workpiece to be measured is magnetized in the magnetization field.

6. The defect detection method based on a ferromagnetic slab as set forth in claim 5, wherein: the magnetizer comprises a U-shaped magnetic yoke and a magnetizing coil, and the magnetizing coil is arranged in the middle of the U-shaped magnetic yoke.

7. The defect detection method based on a ferromagnetic slab as set forth in claim 5, wherein: the magnetizing current in the magnetizing coil is 2A-20A.

8. The defect detection method based on a ferromagnetic slab as set forth in claim 5, wherein: the width of the through groove is 0.025 mm-1 mm.

9. A defect detection method based on a ferromagnetic slab as claimed in any of claims 1 to 4, characterized in that: the magnetic sensor is an induction coil or a Hall element.

10. A defect detection method based on a ferromagnetic slab as claimed in any of claims 1 to 4, characterized in that: the workpiece to be detected is made of a ferromagnetic material.

Technical Field

The invention belongs to the relevant technical field of electromagnetic nondestructive testing, and particularly relates to a defect detection method based on a ferromagnetic plate.

Background

The nondestructive testing technology is a nondestructive testing technology based on electromagnetic induction, and with the development of electronic technology and computer technology, the electromagnetic nondestructive testing technology makes breakthrough progress in development and application, wherein the magnetic flux leakage testing is widely applied to nondestructive testing of ferromagnetic materials. The implementation mode is that an electromagnet or a permanent magnet magnetizes a workpiece, a defect on the workpiece generates disturbance on a magnetic field, so that a leakage magnetic field is generated in the air above the defect, the workpiece is scanned by using a magnetic sensor, so that the existence of the leakage magnetic field is sensed, and then the existence of the defect is judged.

However, in the magnetic flux leakage detection, when the lift-off value of the magnetic sensor is large, the magnetic flux leakage signal is very weak, and when the lift-off value of the magnetic sensor is small, the magnetic sensor may be seriously worn, and mechanical noise caused by vibration of the sensor at a low lift-off value may be large.

Disclosure of Invention

In order to overcome the defects or the improvement requirements of the prior art, the invention provides a defect detection method based on a ferromagnetic plate, wherein a magnetic sensor is fixed on the ferromagnetic plate, and the leakage magnetic field of a through groove or a through hole on the ferromagnetic plate and the leakage magnetic field of the defect of a detected piece are magnetized and mutually enhanced, so that the constant lifting value of the magnetic sensor is realized, the shake is avoided, the wear resistance of the magnetic sensor is enhanced, the leakage magnetic detection signal is enhanced, and the leakage magnetic detection sensitivity is improved.

To achieve the above object, according to one aspect of the present invention, there is provided a defect detecting method based on a ferromagnetic plate, the detecting method comprising the steps of:

(1) fixing a magnetic sensor on a ferromagnetic plate, wherein the ferromagnetic plate is provided with a through groove, the through groove penetrates through the ferromagnetic plate along the thickness direction of the ferromagnetic plate, and the through groove penetrates through the area of the ferromagnetic plate covered by the magnetic sensor;

(2) in a magnetization field, the magnetic sensor and the ferromagnetic plate scan the magnetized workpiece to be detected for defects; and the through groove magnetizes and strengthens the leakage magnetic field generated by the defect on the workpiece to be detected and the leakage magnetic field generated by the defect on the workpiece to be detected mutually under the action of the magnetization field.

Furthermore, the magnetic sensor and the surface of the ferromagnetic plate, which is attached to the workpiece to be detected, move to scan the defect of the workpiece to be detected.

Further, the distance of the magnetic sensor from the surface of the workpiece to be measured is constant.

Further, the lift-off value of the magnetic sensor is a thickness value of the ferromagnetic plate.

Further, an electrified coil or a magnetizer is used to form a magnetization field in which the workpiece to be measured is magnetized.

Further, the magnetizer comprises a U-shaped magnetic yoke and a magnetizing coil, and the magnetizing coil is arranged in the middle of the U-shaped magnetic yoke.

Further, the magnetizing current in the magnetizing coil is 2A-20A.

Further, the width of the through groove is 0.025 mm-1 mm.

Further, the magnetic sensor is an induction coil or a hall element.

Further, the workpiece to be measured is made of a ferromagnetic material.

Generally, compared with the prior art, the defect detection method based on the ferromagnetic plate provided by the invention mainly has the following beneficial effects:

1. fixing a magnetic sensor on a ferromagnetic plate, wherein the ferromagnetic plate is provided with a through groove, the through groove penetrates through the ferromagnetic plate along the thickness direction of the ferromagnetic plate, and the through groove penetrates through the area of the ferromagnetic plate covered by the magnetic sensor, so that when a defect is scanned, a leakage magnetic field generated by the defect is upwards propagated, the magnetization intensity of the through groove is enhanced, and the leakage magnetic field of the through groove is enhanced; meanwhile, the through groove can also generate a leakage magnetic field under the action of a magnetization field, the through groove which is communicated up and down can generate a leakage magnetic field downwards and can also generate a leakage magnetic field upwards, and the downward leakage magnetic field acts on the defect of the workpiece to be detected to strengthen the magnetization of the defect, so that the leakage magnetic field of the defect is enhanced; and the magnetic leakage field that magnetic sensor sensed does the magnetic leakage field of defect with the stack of the magnetic leakage field that leads to the groove makes from this the magnetic leakage field that magnetic sensor sensed has obtained the reinforcing, has improved the sensitivity that detects.

2. The magnetic sensor is fixed on the ferromagnetic plate, and the ferromagnetic plate is attached to a workpiece to be detected to be scanned, so that mechanical noise caused by shaking of the magnetic sensor is avoided, and the wear resistance of the magnetic sensor is enhanced.

3. The ferromagnetic plate is attached to the workpiece to be scanned, so that the distance between the magnetic sensor and the surface of the workpiece to be detected is fixed, the lift-off value of the magnetic sensor is the thickness value of the ferromagnetic plate, the constant lift-off value is guaranteed, the shake of the magnetic sensor is avoided, the stability is good, and the detection sensitivity is improved.

4. The detection method is easy to implement, has high sensitivity, and is 2-4 times of the detection sensitivity of an air stripping method.

Drawings

FIG. 1 is a schematic diagram of a defect detection method based on a ferromagnetic slab according to the present invention;

FIG. 2 is a partial schematic view of a detection apparatus involved in the ferromagnetic slab-based defect detection method of FIG. 1;

FIG. 3 is a schematic diagram of the defect detection method based on a ferromagnetic plate in FIG. 1;

FIG. 4 is a schematic diagram of a simulation model involved in the defect detection method based on the ferromagnetic slab in FIG. 1;

FIG. 5 is a graph comparing the correlation between the magnetization intensity and the leakage magnetic field in the defect detection method based on the ferromagnetic plate in FIG. 1 and the conventional method;

fig. 6 is a comparison graph of the correlation between the through-groove width and the leakage magnetic field in the ferromagnetic plate-based defect detection method in fig. 1 and the conventional method.

The same reference numbers will be used throughout the drawings to refer to the same or like elements or structures, wherein: 1-probe, 2-workpiece to be measured, 3-U-shaped magnetic yoke, 4-magnetizing coil, 1-1-magnetic sensor, 1-2-ferromagnetic plate, 1-3-through groove and 2-1-defect.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

Referring to fig. 1, fig. 2 and fig. 3, the defect detection method based on a ferromagnetic plate according to the present invention mainly includes the following steps:

step one, magnetizing a workpiece to be detected by using a magnetizer so that the defects on the workpiece to be detected generate a leakage magnetic field.

Specifically, the magnetizer used for magnetizing the workpiece 2 to be measured comprises a U-shaped magnetic yoke 3 and a magnetizing coil 4, wherein the magnetizing coil 4 is arranged in the middle of the U-shaped magnetic yoke 3 and is connected to a magnetizing power supply, and the magnetizing power supply supplies power to the magnetizing coil 4. The workpiece 2 to be measured is made of a ferromagnetic material. In addition, magnetization can also be realized by adopting an electrified coil or a permanent magnet magnetizer.

Fixing a magnetic sensor on a ferromagnetic plate, wherein the ferromagnetic plate is provided with a through groove, the through groove penetrates through the ferromagnetic plate along the thickness direction of the ferromagnetic plate, and the through groove penetrates through the area of the ferromagnetic plate covered by the magnetic sensor.

Specifically, the probe 1 is adopted to sense the leakage magnetic field, and then the sensed signal is transmitted to the signal processing device, and the signal processing device processes the received signal to judge the defect. The probe 1 comprises a magnetic sensor 1-1 and a ferromagnetic plate 1-2, wherein the ferromagnetic plate 1-2 is provided with a through groove 1-3, and the through groove 1-3 penetrates through the ferromagnetic plate 1-2. The magnetic sensor 1-1 is arranged on the ferromagnetic plate 1-2, and partially or completely covers one side of the through groove.

In this embodiment, the ferromagnetic plate 1-2 is rectangular, and the through groove 1-3 penetrates through the ferromagnetic plate 1-2 along the thickness direction of the ferromagnetic plate; the depth of the through groove 1-3 is the same as the thickness of the ferromagnetic plate 1-2, and the ferromagnetic plate 1-2 is attached to the workpiece 2 to be detected for scanning, so that the distance from the magnetic sensor 1-1 to the surface of the workpiece 2 to be detected is fixed, and the lift-off value of the magnetic sensor 1-1 is the thickness value of the ferromagnetic plate 1-2. Of course, the through slots 1-3 may also be referred to as through holes.

In a magnetization field, the magnetic sensor and the ferromagnetic plate are attached to the magnetized surface of the workpiece to be detected to move so as to scan the defect of the workpiece to be detected; and the through groove magnetizes and strengthens the leakage magnetic field generated by the defect on the workpiece to be detected and the leakage magnetic field generated by the defect on the workpiece to be detected mutually under the action of the magnetization field.

Specifically, when the probe 1 scans the defect 2-1, the leakage magnetic field generated by the defect 2-1 is upwards propagated, so that the magnetization intensity of the through groove 1-3 is enhanced, and the leakage magnetic field of the through groove 1-3 is enhanced; simultaneously, it also can produce the magnetic leakage field to lead to groove 1-3 under the magnetization field effect, link up from top to bottom lead to groove 1-3 and can produce a magnetic leakage field downwards, upwards also can produce a magnetic leakage field, and decurrent magnetic leakage field is used the 2-1 defects of work piece 2 that awaits measuring and has strengthened defect 2-1's magnetization makes 2-1 defects's magnetic leakage field reinforcing.

The leakage magnetic field sensed by the magnetic sensor 1-1 is the superposition of the leakage magnetic field of the defect 2-1 and the leakage magnetic field of the through groove 1-3, so that the leakage magnetic field sensed by the magnetic sensor 1-1 is enhanced, and the detection sensitivity is improved.

Meanwhile, the magnetic sensor 1-1 is fixed on the ferromagnetic plate 1-2, and the ferromagnetic plate scans the workpiece 2 to be detected, so that mechanical noise caused by shaking of the magnetic sensor 1-1 is avoided, and the wear resistance of the magnetic sensor is enhanced.

Referring to fig. 4, 5 and 6, to further illustrate the present invention, a finite element model simulation is performed by using simulation software, wherein the model is composed of a magnetizing coil, a workpiece to be measured, and a ferromagnetic filling layer with a through groove, the magnetizing coil provides magnetization for the workpiece to be measured and the filling layer, the number of turns is 2000 turns, and the magnetizing current is I. The materials of the workpiece to be measured and the filling layer are set to be 45#, the magnetization constitutive relation is set to be a B-H curve, the defect depth is H, and the width is B_cThe filling thickness of the lift-off layer is t, and the width of the through groove is b_s. The measuring point is a position which is 0.2mm away from the surface of the through groove and is right above the center of the defect. The change range of the magnetization current is 2A-20A, preferably 16A.

In the embodiment, air lift-off and slotting lift-off are simulated respectively, and the leakage magnetic field at the position of 1mm above the defect is obtained under each magnetizing currentComponent B in the horizontal direction_xSubtracting the background magnetic field to obtain a leakage magnetic field peak value; according to the self-simulation result, under different magnetization intensities, the signal amplitude of the detection method provided by the application is always larger than that of the air lift-off method.

In another simulation example, the magnetizing current is set to be 16A, the defect width is set to be 0.3mm, the variation range of the width of the through groove is 0.025 mm-1 mm, preferably 0.25mm, and the simulation model is the same as the simulation model; from the simulation result, along with the increase of the width of the through groove, the strength of the leakage magnetic field is increased and then reduced, and the signal amplitude of the detection method provided by the application is always larger than that of an air lift-off method, so that the detection method can achieve higher detection sensitivity.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.