Ferromagnetic material local stress distribution nondestructive testing device based on MDL
阅读说明:本技术 一种基于mdl的铁磁材料局部应力分布无损检测装置 (Ferromagnetic material local stress distribution nondestructive testing device based on MDL ) 是由 裴延玲 梁凯铭 毕晓昉 李树索 宫声凯 伊万卓罗斯·赫里斯道法奥柔 于 2019-10-25 设计创作,主要内容包括:本发明公开了一种基于MDL的铁磁材料局部应力分布无损检测装置,包括具有均匀横截面的MDL、激励线圈、检测线圈、永磁体、支撑件以及超声回波探测器,所述MDL平置于被测铁磁材料上方;所述激励线圈和所述检测线圈分别绕置于所述MDL周围,所述激励线圈和所述检测线圈之间的距离配置成避免激励线圈的激励信号和检测线圈的检测信号发生干扰;所述永磁体固定于所述MDL的上表面;所述支撑件设置于所述MDL与被测铁磁材料之间,用以支撑所述MDL及所述永磁体;所述超声回波探测器通过所述支撑件上预设的通孔与被测铁磁材料贴合,用以探测被测铁磁材料的厚度。本发明可以实现局部区域或连续区域的快速检测,同时保证高精度高灵敏度。(The invention discloses a nondestructive testing device for local stress distribution of a ferromagnetic material based on an MDL (medium density distribution), which comprises an MDL with a uniform cross section, an excitation coil, a detection coil, a permanent magnet, a support piece and an ultrasonic echo detector, wherein the MDL is horizontally arranged above the ferromagnetic material to be tested; the excitation coil and the detection coil are respectively wound around the MDL, and the distance between the excitation coil and the detection coil is configured to avoid interference of an excitation signal of the excitation coil and a detection signal of the detection coil; the permanent magnet is fixed on the upper surface of the MDL; the support piece is arranged between the MDL and the ferromagnetic material to be tested and used for supporting the MDL and the permanent magnet; the ultrasonic echo detector is attached to the ferromagnetic material to be detected through a through hole preset in the supporting piece and used for detecting the thickness of the ferromagnetic material to be detected. The invention can realize the rapid detection of local areas or continuous areas and simultaneously ensure high precision and high sensitivity.)
1. A nondestructive testing device for local stress distribution of ferromagnetic materials based on MDL is characterized by comprising the MDL with a uniform cross section, an excitation coil, a detection coil, a permanent magnet, a support and an ultrasonic echo detector,
the MDL is horizontally arranged above the ferromagnetic material to be tested; the excitation coil and the detection coil are respectively wound around the MDL, and the distance x between the excitation coil and the detection coil is configured to avoid interference of an excitation signal of the excitation coil and a detection signal of the detection coil; the permanent magnet is fixed on the upper surface of the MDL; the support piece is arranged between the MDL and the ferromagnetic material to be tested and used for supporting the MDL and the permanent magnet; the ultrasonic echo detector is attached to the ferromagnetic material to be detected through a through hole preset in the supporting piece and used for detecting the thickness of the ferromagnetic material to be detected.
2. The method according to claim 1, wherein the excitation coil and the detection coil are wound around both ends of the MDL, respectively, and the permanent magnet is fixed to a central portion of an upper surface of the MDL.
3. The method according to claim 1, wherein the excitation coil and the detection coil are wound around the same end of the MDL, the permanent magnet is fixed to the other end of the MDL, and the excitation coil is interposed between the detection coil and the permanent magnet.
4. Method according to one of claims 1-3, characterized in that the distance x between the excitation coil and the detection coil is expressed as:
x=Tci-l
wherein, T is the oscillation duration, namely the frequency, of the input pulse current; c. CiIs the propagation velocity of sound waves in the MDL; l is the length of the excitation coil.
5. The method according to one of claims 1 to 3, wherein the permanent magnet is a cylindrical Nd-Fe permanent magnet oriented in the S-N direction, and the magnetic force between the permanent magnet and the ferromagnetic material to be measured is:
F=(3πKdR2/4)τ2/(τ+γ)4
wherein the content of the first and second substances,
6. A method according to any one of claims 1 to 3, wherein the support member is an aluminium support plate.
7. A method according to any one of claims 1 to 3, wherein a lubricant is provided between the support and the ferromagnetic material being measured.
8. The method of any one of claims 1 to 3, wherein the MDL is single-surface bonded to the upper surface of the support member by an acrylic adhesive, and the permanent magnet is single-surface bonded to the upper surface of the MDL by an acrylic adhesive.
9. The method of any one of claims 1-3, wherein said MDL is an Fe78Si7B15 amorphous magnetostrictive strip.
Technical Field
The invention belongs to the field of nondestructive testing of local stress distribution of ferromagnetic materials, and particularly relates to a nondestructive testing device for local stress distribution of ferromagnetic materials based on magnetostrictive delay strips (MDL).
Background
Stress detection is very important in the field of modern industrial production and processing, and particularly has important influence and engineering significance on the detection of the service life and the material reliability of a product by using a local stress detection technology on the surface and the inside of a material. The presence of residual stresses can seriously affect the strength and related properties of the workpiece, mainly due to internal stresses remaining inside the material after mechanical and thermal processing and maintaining internal equilibrium, if not processed, during the use of the material, the internal stress equilibrium of the material is destroyed due to uneven heat treatment, welding or cutting, etc., and the stress level exceeds the strength limit to cause cracks or material failure. The existing non-destructive testing technology for residual stress mainly comprises testing means such as an X-ray or neutron ray diffraction method, a magnetic testing method, an ultrasonic testing method and the like. Among them, X-ray and neutron diffraction methods are the most reliable stress detection methods, but these two techniques require a lot of infrastructure and time, and each detection can only complete the measurement of stress parameters in several mm regions, which is time-consuming and costly.
The magnetic measurement method is a novel detection method developed in recent years, and mainly utilizes the magnetostrictive effect of ferromagnetic materials, the magnetostrictive coefficient is anisotropic, and the magnetic domain magnetization direction is the characteristic of easy magnetization axis direction, so that the internal stress of the material to be detected generates magnetic anisotropy under the action of a magnetic field. The residual stress level is finally obtained by detecting and collecting signals through a sensor and a test circuit. The existing detection technology is composed of a detection probe, a circuit, a software computer, a power supply and the like. During testing, the flatness and the cleanliness of the surface of a material to be tested need to be guaranteed, a material area is detected and scanned through a grid dividing and other means, and the average stress level of the area is finally obtained through software calculation and synthesis.
However, various devices applied to the existing magnetic measurement method have the detection principle that after a whole material area is scanned, the average profit level under a single probe is obtained according to the calculation of calculation software, and then a stress level curve of the whole area is generated, so that the obtained detection result is the result after averaging and simulation, the material has the size limitation, the detection speed is slow, and the actual detection precision is not high enough.
Disclosure of Invention
Therefore, the invention designs a new internal structure of the detection probe by applying the MDL technology, can realize the rapid detection of a local area or a continuous area, and simultaneously ensures high precision and high sensitivity.
The invention provides a nondestructive testing device for local stress distribution of a ferromagnetic material based on an MDL (medium density distribution), which comprises the MDL with a uniform cross section, an excitation coil, a detection coil, a permanent magnet, a support and an ultrasonic echo detector,
the MDL is horizontally arranged above the ferromagnetic material to be tested; the excitation coil and the detection coil are respectively wound around the MDL, and the distance between the excitation coil and the detection coil is configured to avoid interference of an excitation signal of the excitation coil and a detection signal of the detection coil; the permanent magnet is fixed on the upper surface of the MDL; the support piece is arranged between the MDL and the ferromagnetic material to be tested and used for supporting the MDL and the permanent magnet; the ultrasonic echo detector is attached to the ferromagnetic material to be detected through a through hole preset in the supporting piece and used for detecting the thickness of the ferromagnetic material to be detected.
In some embodiments, the excitation coil and the detection coil may be wound around both ends of the MDL, respectively, and the permanent magnet is fixed to a middle portion of an upper surface of the MDL.
In some embodiments, the excitation coil and the detection coil may be wound around the same end of the MDL, the permanent magnet is fixed to the other end of the MDL, and the excitation coil is interposed between the detection coil and the permanent magnet.
In some embodiments, the distance x between the excitation coil and the detection coil may be expressed as:
x=Tci-l
wherein, T is the oscillation duration, namely the frequency, of the input pulse current; c. CiIs the propagation speed of sound wave in the MDL medium; l is the length of the excitation coil.
In some embodiments, the permanent magnet is a cylindrical Nd-Fe permanent magnet with the direction along the S-N direction, and the magnetic force between the permanent magnet and the ferromagnetic material to be measured is as follows:
F=(3πKdR2/4)τ2/(τ+γ)4
wherein the content of the first and second substances,
shows the magnetostatic energy density of the magnetic field of the Nd-Fe permanent magnet; mu.s0Represents the vacuum permeability; m0Is the saturation magnetization of Nd-Fe permanent magnet; r represents the bottom surface radius of the Nd-Fe permanent magnet; τ ═ d/R represents the aspect ratio of the Nd — Fe permanent magnet; γ ═ z0-d)/R represents the ratio of the gap distance between the magnetic pole of the Nd-Fe permanent magnet and the ferromagnetic material to be measured to the radius of the bottom surface of the Nd-Fe permanent magnet, wherein d represents the height of the magnetic pole of the Nd-Fe permanent magnet from the end surface thereof and the ferromagnetic material to be measured camera, namely half of the height of the cylinder of the Nd-Fe permanent magnet, z0The spatial position, i.e. the relative distance, of the magnetic pole of the Nd-Fe permanent magnet relative to the ferromagnetic material to be measured is shown. The gap distance refers to the distance from the end face of the Nd-Fe permanent magnet close to the ferromagnetic material to be measured to the surface of the ferromagnetic material to be measured, and comprises the thickness of the MDL and the supporting piece which are arranged between the Nd-Fe permanent magnet and the ferromagnetic material to be measured.In some embodiments, the support may be an aluminum support plate or other non-ferromagnetic material.
In some embodiments, a lubricant may be disposed between the support and the ferromagnetic material being measured.
In some embodiments, the MDL may be single-surface-bonded to the upper surface of the supporter by an acrylic adhesive, and the permanent magnet may be single-surface-bonded to the upper surface of the MDL by an acrylic adhesive.
In some embodiments, the MDL may be an Fe78Si7B15 amorphous magnetostrictive strip.
The invention has the beneficial effects that:
1) the invention relates to a stress MDL technology, wherein a permanent magnet applies a magnetic field on a ferromagnetic material to be tested, because of different local magnetic conductivities, the pressure applied on the MDL between the ferromagnetic material and the permanent magnet is different, and different signals are output by utilizing the high sensitivity of a high-magnetism-induction amorphous strip to magnetostriction change, thereby realizing the stress test of a fixed-point area and the stress test of a continuous area.
2) The invention utilizes MDL technology, can obtain detection data without converting the relative angle between the equipment and the detected material, can realize quick detection because the magnetization process is quick and the detection process has no delay, and can be applied to a factory detection production line of industrial production and can quickly evaluate the stress level of the equipment when large-scale equipment is overhauled.
3) The detection device of the invention has lower cost and can be applied to a factory and other detection conditions in a large scale.
Drawings
FIG. 1 is a schematic structural diagram of an MDL-based nondestructive testing apparatus for localized stress distribution of ferromagnetic materials according to an embodiment of the present invention;
FIG. 2 is a circuit diagram of a signal processing module according to the present invention;
FIG. 3 is a schematic structural diagram of an MDL-based nondestructive testing apparatus for localized stress distribution of ferromagnetic materials according to another embodiment of the present invention;
FIG. 4 is a graph showing the result of detecting the local permeability change of the ferromagnetic material under test by using the detecting device of FIG. 1;
FIG. 5 is a graph showing the result of detecting the local permeability change of the ferromagnetic material to be detected by the detecting device of FIG. 3;
fig. 6 is a graph showing a comparison between the stress detection result of the steel welding region and the actual stress distribution by the detection device of the present invention.
Detailed Description
The invention is further described below with reference to the accompanying drawings and examples, it being understood that the examples described below are intended to facilitate the understanding of the invention, and are not intended to limit it in any way.
As shown in fig. 1, the MDL-based nondestructive testing device for local stress distribution of ferromagnetic material according to an embodiment of the present invention includes an MDL1 having a uniform cross section, an
In the example shown in fig. 1, the MDL1 is placed horizontally above the
When the
Abnormal residual stress is generated in the measured
In particular, an
In particular, the Nd-Fe
F=(3πKdR2/4)τ2/(τ+γ)4
wherein the content of the first and second substances,
shows the magnetostatic energy density of the magnetic field of the Nd-FeSpecifically, the Nd — Fe
In particular, a
Fig. 3 shows a schematic structural diagram of an MDL-based nondestructive testing apparatus for local stress distribution of ferromagnetic material according to another embodiment of the present invention, which is the same as the example shown in fig. 1 except that the relative positions of the
The invention is further explained by the test result graph of the local magnetic permeability change of the tested ferromagnetic material by the test device of the invention, firstly, specific parameter values are given, in the examples of fig. 1 and fig. 3, the MDL1 is an Fe78Si7B15 amorphous magnetostrictive strip, the width, the length and the thickness of which are respectively 6mm, 100mm and 25 μm; the
Fig. 6 is a graph showing a comparison of the stress detection result of the steel welding region with the actual stress distribution using the detection apparatus of the present invention. As can be seen from the figure, for a near-hot base area, a heat affected area and a fusion area of a steel welding area from left to center, the residual stress level distribution of steel is increased due to welding heat treatment, a dot diagram is the residual stress level distribution obtained by an XRD (X-ray diffraction method) detection means, a dot diagram is an output result obtained by the detection of the sensor, the shapes of the distribution curves obtained by the two detection means are basically consistent, and the reliability of the detection result of the sensor is verified through the results of examples.
It will be apparent to those skilled in the art that various modifications and improvements can be made to the embodiments of the present invention without departing from the inventive concept thereof, and these modifications and improvements are intended to be within the scope of the invention.
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