CN111289570A - Component coating debonding nondestructive testing device - Google Patents

Abstract

The invention discloses a non-destructive testing device for component coating debonding. It includes: a high voltage power supply, a narrow pulse generator, a first electrode, a second electrode, a film cover, and a piezoelectric film inside the film cover; the high voltage power supply applies a high voltage to the first electrode, and the narrow pulse generator applies a narrow pulse to the first electrode signal; the second electrode is connected to the high-voltage power supply and the ground terminal of the narrow pulse generator; the film cover is made of conductive material and plays the role of electromagnetic shielding. When the component is a metal component, the first electrode is the body part of the metal component; when the component is a polymer component, the detection device further includes: a metal plate, the metal plate is used as the first electrode and The body portions of the polymeric members conform to each other. The invention determines the debonding condition of the component coating by analyzing the ultrasonic wave (or stress wave) signal detected by the piezoelectric film, and realizes the non-destructive detection of the debonding condition of the component coating.

Description

A non-destructive testing device for component coating debonding

technical field

The invention relates to the field of nondestructive testing, in particular to a nondestructive testing device for component coating debonding.

Background technique

At present, in order to improve the performance properties and application range of metals and improve the wear resistance, corrosion resistance, high temperature resistance and other characteristics of polymers, a layer of ceramic or other insulating materials is often sprayed on the metal surface or the polymer surface. However, debonding of the coating can seriously affect the application of metallic or polymeric components. And because the coating is relatively thin, when using the classical ultrasonic detection to detect the debonding, there are the problems of weak detection signal and surface blind area, which increases the detection difficulty.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a non-destructive testing device for the debonding of insulating coatings of components.

For achieving the above object, the present invention provides the following scheme:

A non-destructive testing device for component coating debonding, comprising: a high-voltage power supply, a narrow pulse generator, a first electrode and a second electrode, a film cover, and a piezoelectric film arranged inside the film cover;

The high-voltage power supply is connected to the first electrode through a high-voltage resistor, and is used for applying a high-voltage DC voltage to the first electrode;

The narrow pulse generator is connected to the first electrode through a high-voltage capacitor, and is used to apply a narrow pulse with a width smaller than a set value to the first electrode;

the second electrode is connected to the high-voltage power supply and the ground terminal of the pulse generator;

The film cover is made of conductive material and plays the role of electromagnetic shielding. The electric film is attached, and the film cover is also connected with the second electrode; the component to be tested includes a body part and the insulating coating part;

The piezoelectric film is used to convert the induced stress wave into a voltage signal; the debonding condition of the insulating coating of the component under test is obtained by analyzing the voltage signal;

When the measured component is a metal component, the first electrode is a body part of the metal component; when the measured component is a polymer component, the detection device further comprises: a metal plate, the metal A plate is attached to the body portion of the polymer member as the first electrode.

Optionally, the detection device further includes: a wave absorbing block disposed in the film cover, the wave absorbing block being attached to the piezoelectric film.

Optionally, the detection device further includes: a rubber pad disposed between the inner bottom surface of the film cover and the wave absorbing block.

Optionally, the detection device further includes an adjusting bolt, the second electrode is a casing with an upward opening, the membrane cover is arranged in the casing, and a bottom surface of the casing is provided with a casing that is open to the adjusting bolt. The tightening bolts are matched with threaded holes, and the tightening bolts pass through the threaded holes on the bottom surface of the casing from the outside of the casing, and abut the bottom surface of the membrane cover.

Optionally, a positioning ring integrally formed with the casing is provided on the inner side of the bottom of the casing, the film cover is arranged in the positioning ring, and a positioning ring is provided between the positioning ring and the side wall of the film cover. gasket.

Optionally, the detection device further includes a rubber gasket, and the edge of the casing is sealedly connected with the insulating coating part of the component under test through the rubber gasket.

Optionally, an intake pipeline and an exhaust pipeline are provided on the housing, and the exhaust pipeline is connected to a vacuum pump.

Optionally, the detection device further includes an intake valve and an exhaust valve, the intake valve is arranged on the intake pipeline, and the exhaust pipeline is connected to the vacuum pump through the exhaust valve.

Optionally, the detection device further includes a signal amplifier, and the piezoelectric film is connected to a signal analysis device through the signal amplifier.

Optionally, the signal analysis device includes an oscilloscope and/or a computer.

According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects: the non-destructive testing device for component coating debonding provided by the present invention utilizes the characteristics of insulation and easy polarizability of the insulating coating, and applies a high electric field to it. And the narrow pulse signal, under the action of high electric field, polarized charges will appear on the debonding surface of the insulating coating, and the polarized charges will be excited under the action of the narrow pulse signal to generate stress waves. Determine whether there is debonding of the coating, and realize the non-destructive testing of the debonding of the insulating coating of the component.

Description of drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings required in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some of the present invention. In the embodiments, for those of ordinary skill in the art, other drawings can also be obtained according to these drawings without any creative effort.

1 is a schematic structural diagram of a non-destructive testing device for metal component coating debonding in an embodiment of the present invention;

2 is a schematic structural diagram of a non-destructive testing device for polymer component coating debonding in an embodiment of the present invention;

Fig. 3(a) is a schematic diagram of a component with debonding defects in an insulating coating in an embodiment of the present invention, and Fig. 3(b) is a test curve diagram of the component shown in Fig. 3(a).

1. High voltage capacitor, 2. High voltage resistor, 3. First electrode, 4. Second electrode, 5. Rubber gasket, 6. Film cover, 7. Insulating coating part, 8. Piezoelectric film (PVDF film) 9. Absorber block, 10, rubber pad, 11, gasket, 12, adjusting bolt, 13, intake valve, 14, exhaust valve, 15, signal amplifier, 16 positioning ring.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

In order to make the above objects, features and advantages of the present invention more clearly understood, the present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

The present invention provides a non-destructive testing device for component coating debonding. As shown in FIG. 1, the testing device includes: a high-voltage power supply, a narrow pulse generator, a first electrode 3, a second electrode 4, a film cover 6, and a The piezoelectric film 8 inside the film cover 6; wherein, the component to be tested includes a body part and an insulating coating part 7 sprayed on the surface of the body part; the high-voltage power supply is connected to the first electrode 3 through a high-voltage resistor 2, and uses To apply a high voltage that can exceed tens of thousands of volts to the first electrode 3; The narrow pulse of the set value (generally less than 50 nanoseconds, such as 10 nanoseconds can be selected); the second electrode 4 is connected to the DC high voltage power supply and the grounding end of the pulse generator; the film cover 6 , made of conductive material (such as aluminum), the upper end surface (thickness can be 5-10mm), the inner and outer surfaces are parallel, the outer surface is attached to the insulating coating on the surface of the component to be measured, and the inner surface is connected to the piezoelectric film 8 that receives the measurement signal. The film cover 6 is also connected to the second electrode 4, so that the film cover 6 and the second electrode 4 are connected; the piezoelectric film 8 (PVDF film) is used to convert the induced stress wave is the voltage signal. By analyzing the voltage signal, it is obtained whether there is debonding of the insulating coating of the component under test.

When the measured component is a metal component, as shown in FIG. 1 , the first electrode 3 is the body part of the metal component; when the measured component is a polymer component, as shown in FIG. 2 , The detection device further includes: a metal plate, which serves as the first electrode 3 and is attached to the body portion of the polymer member. Metal plates and polymer components can be temporarily fixed by means of temporary bonding or support.

In this embodiment, under the action of an external electric field, the insulating coating of the component under test will be polarized, and the density of polarized charges on the surface of the internal defect will be higher than that of other parts. ), causing a short-term sudden change in the applied electric field, the charge of the insulating coating will vibrate, and a series of stress waves (mainly longitudinal waves) will be formed. The larger the charge density, the larger the amplitude of the position wave. If the piezoelectric film 8 detects a corresponding stress wave, it means that the insulating coating of the component under test has a debonding defect.

In this embodiment, the detection device may further include: a wave absorbing block 9 disposed in the film cover 6 , and the wave absorbing block 9 is attached to the piezoelectric film 8 . The wave absorbing block 9 plays the role of absorbing sound waves, preventing the reflected signal from interfering with the output signal, and the material can be selected from plexiglass.

In this embodiment, the detection device may further include: a rubber pad 10 , and the rubber pad 10 is disposed between the inner bottom surface of the film cover 6 and the wave absorbing block 9 . By adjusting the thickness of the rubber pad 10, adjust the strength of the wave absorbing block 9 to press the piezoelectric film 8, so as to avoid that the pressure is too large to close the defects of the component under test, the positive and negative charges induced by the external electric field are neutralized, and the pressure is too small As a result, the component under test is not tightly attached to the electrode, which is not conducive to the passage of stress waves.

In this embodiment, the detection device may further include an adjusting bolt 12, the second electrode 4 may be a casing with an upward opening, the membrane cover 6 is arranged in the casing, and the bottom surface of the casing is provided with an adjusting bolt 12 Matching threaded holes, the tightening bolts 12 pass through the threaded holes on the bottom surface of the casing from the outside of the casing, and top the bottom surface of the membrane cover 6 . At this time, the membrane cover 6 and the second electrode 4 are electrically connected through the tightening bolt 12 , that is, the membrane cover 6 and the second electrode 4 are electrically connected through the tightening bolt 12 . In this embodiment, the contact pressure between the film cover 6 and the insulating coating is adjusted by adjusting the tightening bolt 12 to ensure that the film cover 6 and the insulating coating are closely attached. The shape of the shell of the second electrode 4 also plays the role of electromagnetic shielding.

In this embodiment, a positioning ring 16 integrally formed with the casing can be provided inside the bottom of the casing to position the film cover 6 . Preferably, the size of the positioning ring 16 is the same as the shape of the film cover 6 . size to match. The film cover 6 is arranged in the positioning ring 16 , and a sealing gasket 11 is arranged between the positioning ring 16 and the side wall of the film cover 6 . In an embodiment, the detection device may further include: a rubber gasket 5 , through which the edge of the casing is sealedly connected with the insulating coating part 7 of the component under test. Among them, the gasket 11 between the positioning ring 16 and the side wall of the film cover 6 and the rubber gasket 5 between the edge of the casing and the insulating coating part of the component under test play a role in sealing the inner space of the casing.

On the basis of the previous embodiment, this embodiment is further provided with an intake pipeline and an exhaust pipeline on the casing, the intake pipeline is provided with an intake valve 13, and the exhaust pipeline passes through the exhaust valve. 14 Connect with the vacuum pump. Before the experiment, close the intake valve 13, and use a vacuum pump to pump the inside of the casing to a negative pressure. The sealed state in the casing can keep the negative pressure, so that the coating can be separated from the component at a certain distance at the defect, so as to prevent the polarized charge from being The surface of the test component is bleed off, making it easier to measure the defect.

In this embodiment, the detection device may further include a signal amplifier 15 , and the piezoelectric film 8 is connected to a signal analysis device through the signal amplifier 15 . Wherein, the signal analysis device may include an oscilloscope and/or a computer.

Figure 3(a) shows a component with a debonding defect in the insulating coating. If the component has a coating debonding defect, after the inside of the shell is pumped to a negative pressure, the coating that is easier to debond is separated from the component body. A DC high voltage is applied between the electrodes to polarize the component, and equal and opposite charges are induced on the outer surface of the coating and at the interface between the coating and the component body. Figure 3(b) shows the stress wave curve measured by the PVDF film after the narrow pulse is applied. The first peak of the curve is the charge stress pulse wave that appears at the outer surface of the coating. The second wave peak is the charge stress pulse wave (the wave generated by the debonding of the coating) that appears at the interface between the coating and the component body. As long as there is a second wave, it means that there is debonding. Since the defect is the wave source, the emitted wave has not undergone any reflection or transmission, so a clean and regular stress wave can be measured through the piezoelectric film 8 .

The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the various embodiments can be referred to each other.

In this paper, specific examples are used to illustrate the principles and implementations of the present invention. The descriptions of the above embodiments are only used to help understand the methods and core ideas of the present invention; meanwhile, for those skilled in the art, according to the present invention There will be changes in the specific implementation and application scope. In conclusion, the contents of this specification should not be construed as limiting the present invention.

Claims (10)

1. A component coating debonding nondestructive testing apparatus, comprising: the device comprises a high-voltage power supply, a narrow pulse generator, a first electrode, a second electrode, a film cover and a piezoelectric film arranged in the film cover;

the high-voltage power supply is connected with the first electrode through a high-voltage resistor and is used for applying direct-current high voltage to the first electrode;

the narrow pulse generator is connected with the first electrode through a high-voltage capacitor and used for applying a narrow pulse with the width smaller than a set value to the first electrode;

the second electrode is connected with the high-voltage power supply and the grounding end of the pulse generator;

the film cover is made of a conductive material and plays a role of electromagnetic shielding, the outer side face of the upper end of the film cover is attached to the insulating coating part of the tested member, the inner side face of the upper end of the film cover is attached to the piezoelectric film, and the film cover is also connected with the second electrode; the measured member includes a body portion and the insulating coating portion;

the piezoelectric film is used for converting the induced stress wave into a voltage signal; analyzing the voltage signal to obtain the debonding condition of the insulating coating of the tested component;

when the measured member is a metal member, the first electrode is a body portion of the metal member; when the member to be detected is a polymer member, the detection apparatus further includes: a metal plate as the first electrode attached to the body portion of the polymer member.

2. The component coating debonding nondestructive inspection device of claim 1, wherein the inspection device further comprises: the wave absorbing block is arranged in the film cover and is attached to the piezoelectric film.

3. The component coating debonding nondestructive inspection device of claim 2, wherein the inspection device further comprises: the rubber pad is arranged between the bottom surface of the inner side of the film cover and the wave absorbing block.

4. The component coating debonding nondestructive inspection device according to claim 1, wherein the inspection device further comprises a tightening bolt, the second electrode is an upward-opening housing, the thin film cover is disposed in the housing, a bottom surface of the housing is provided with a threaded hole matching with the tightening bolt, and the tightening bolt penetrates through the threaded hole of the bottom surface of the housing from outside the housing and abuts against a bottom surface of the thin film cover.

5. The component coating debonding nondestructive testing apparatus according to claim 1, wherein a positioning ring integrally formed with the housing is disposed on an inner side of the bottom of the housing, the film cover is disposed in the positioning ring, and a sealing gasket is disposed between the positioning ring and a side wall of the film cover.

6. The device for nondestructive testing of component coating debonding according to claim 5, wherein the device further comprises a rubber gasket, and the housing edge is sealingly connected to the insulating coating portion of the component under test via the rubber gasket.

7. The component coating debonding nondestructive testing apparatus according to claim 6, wherein an air inlet pipeline and an exhaust pipeline are arranged on the housing, and the exhaust pipeline is connected with a vacuum pump.

8. The component coating debonding nondestructive testing apparatus according to claim 7, wherein the testing apparatus further comprises an air inlet valve and an air outlet valve, the air inlet valve is disposed on the air inlet pipeline, and the air outlet pipeline is connected with a vacuum pump through the air outlet valve.

9. The component coating debonding nondestructive inspection apparatus of claim 1, wherein the inspection apparatus further comprises a signal amplifier through which the piezoelectric film is connected to a signal analysis device.

10. The component coating debonding nondestructive inspection apparatus of claim 9, wherein the signal analysis device comprises an oscilloscope and/or a computer.

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