Engine compressor blade nondestructive testing device

Abstract

The present invention relates to a nondestructive testing device for an engine compressor blade, comprising a connecting rod, one end of which is connected to a probe, and a handle is provided on the rod body of the connecting rod, the handle being able to slide on the rod body, and the probe being able to prevent the handle from sliding out; the probe comprising a detection coil for detecting whether a current signal in the coil changes; a detection surface being provided on the probe; the detection surface being provided with a bevel portion and an angled portion, the bevel portion and the angled portion being engaged, and a spring forming a movable constraint between the bevel portion and the angled portion. The nondestructive testing device for an engine compressor blade provided by the present invention does not require any surface pretreatment of the object to be tested, does not require the application of a coupling agent, and realizes non-contact rapid testing, and the bevel portion and the angled portion are connected by a spring, so that convenient and rapid testing can be performed without disassembly, and cracks can be successfully detected. The nondestructive testing device for an engine compressor blade provided by the present application is sensitive in response and has a good detection effect.

Description

Technical Field

[0001] The present invention belongs to the technical field of non-destructive testing, and in particular relates to a non-destructive testing device for engine compressor blades. Background Art

[0002] The establishment and development of the basic principles of eddy current testing technology originated from early discoveries in electromagnetism. In 1824, Gabet discovered that a copper plate would impede the swing of a suspended magnet. In 1828, Foucault pointed out the existence of eddy currents and the accompanying thermal effects within a copper disk moving in a strong, inhomogeneous magnetic field. However, many questions remained until 1831, when Faraday discovered the phenomenon of electromagnetic induction, which states that a changing magnetic field can generate an electric field, and formulated the law of electromagnetic induction. To this day, electromagnetic induction is used to illustrate the important objective law underlying the basic principles of eddy current testing. Since its discovery, extensive research has led to significant progress in both experimental research on electromagnetic phenomena and mathematical analysis of fundamental electromagnetic theory. In 1873, Maxwell systematically summarized and developed the achievements of his predecessors in the field of electromagnetics, revising the equations describing the fundamental principles of electromagnetism to form the Maxwell equations. Maxwell's equations rigorously describe all macroscopic electromagnetic phenomena and are the basic theoretical tool for solving most electromagnetic problems. By analyzing Maxwell's equations for specific problems with appropriate boundary conditions, it is possible, in principle, to calculate the distribution of current or fields inside and on the surface of objects of different shapes and materials.

[0003] In the prior art, engine blades are made of non-magnetic metal. The blade edge, blade basin, and blade back are stress concentration areas located 1 / 3 to 1 / 2 of the blade height, making them prone to fatigue and fatigue cracking. Cracks are oriented radially. Blade defect inspection is a specialized environment. During routine aircraft maintenance, mechanics typically inspect engine blades within the air intake duct, limiting operational space. Because the inspection targets are engine compressor blades, disassembly inspection is typically not performed during maintenance, limiting the available inspection methods. Commonly used non-destructive testing methods in aviation maintenance include ultrasonic, magnetic particle, eddy current, radiographic, and penetrant testing. Magnetic particle, eddy current, and penetrant testing are the primary methods used to detect surface fatigue cracks. However, magnetic particle testing relies on the leakage field at the defect site to attract magnetic particles, forming magnetic traces that can be detected to determine the presence of surface and near-surface defects. This makes it difficult to perform without disassembling the blade, and magnetic particle testing can only inspect ferromagnetic parts. Penetrant testing places high demands on the surface of the test object, requiring it to be relatively smooth and free of contamination, and requires pre-treatment of the surface before testing. This method is limited to detecting discontinuities of surface openings, is easily affected by temperature, has a complex procedure, poor repeatability, and is not suitable for use. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to overcome the shortcomings of the prior art and provide a non-destructive testing device for engine compressor blades to solve the problem that the detection device for detecting engine compressor blades in the prior art is inconvenient to use for detecting the front and back sides of the blades without disassembling the blades.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a nondestructive testing device for an engine compressor blade, comprising: a connecting rod, one end of which is connected to a probe and a handle is provided on the connecting rod body, the handle being able to slide on the rod body, and the probe being able to prevent the handle from sliding out;

[0006] The probe includes a detection coil for detecting whether the current signal in the coil changes;

[0007] The probe is provided with a detection surface;

[0008] The detection surface is provided with an oblique groove portion and an oblique angle portion, the oblique groove portion and the oblique angle portion are clamped together, and a spring forms a movable constraint between the oblique groove and the oblique angle portion.

[0009] Furthermore, the detection coil includes a wire and a coil;

[0010] The detection coil adopts an absolute detection coil or a transformer type coil.

[0011] Furthermore, the absolute detection coil includes:

[0012] The excitation coil and the induction coil are connected in parallel.

[0013] Furthermore, the detection coil is provided with

[0014] Magnetic core, used to enhance the magnetic field strength in the detection area.

[0015] Furthermore, the detection frequency of the probe is 400kHz to 1800kHz;

[0016] When the AC resistance of the wire is equal to the resistance caused by the proximity effect when only the skin effect is considered at a given frequency, the diameter of the excitation coil wire is 0.08 mm;

[0017] The diameter of the coil is approximately 1.2 times the diameter of the magnetic core;

[0018] The number of turns of the excitation coil is 28 to 35, and the number of turns of the induction coil is 14 to 20;

[0019] The minimum distance between the excitation coil and the induction coil is 3.32 mm.

[0020] Furthermore, the detection frequency of the probe is 1200kHz;

[0021] The number of turns of the excitation coil is 32, and the number of turns of the induction coil is 16.

[0022] Furthermore, the length of the connecting rod is 300 mm;

[0023] The length of the handle is 130 mm;

[0024] The volume of the probe is 15*15*20mm 3 .

[0025] The present invention adopts the above technical solution, and the beneficial effects that can be achieved include:

[0026] The present invention provides a nondestructive testing device for an engine compressor blade, comprising a connecting rod, one end of which is connected to a probe, and a handle provided on the shaft of the connecting rod. The handle can slide on the shaft, and the probe can prevent the handle from sliding out; the probe includes a detection coil for detecting whether the current signal in the coil changes. The nondestructive testing device for an engine compressor blade provided by the present invention does not require any surface pretreatment of the object being tested, and does not require the application of a coupling agent, thereby achieving non-contact rapid testing. The bevel portion and the bevel portion are connected by a spring, enabling convenient and rapid testing without disassembly, and successfully detecting cracks. The nondestructive testing device for an engine compressor blade provided by the present application is sensitive and has a good detection effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 A schematic structural diagram of the connecting rod and the probe provided by the present invention;

[0029] Figure 2 A schematic diagram of the structure of the handle provided by the present invention;

[0030] Figure 3 This is a schematic diagram of the relationship between the resistance and diameter of the wire provided by the present invention. DETAILED DESCRIPTION

[0031] To make the objectives, technical solutions, and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other implementations obtained by those of ordinary skill in the art without inventive effort are within the scope of protection of the present invention.

[0032] The present application provides a non-destructive testing device for engine compressor blades, which is mainly used to detect surface cracks in materials, which are discontinuous defects. It is an application of eddy current testing methods. The principle of eddy current testing is that an electric field can excite a magnetic field in space, and a changing magnetic field can excite an electric field. Placing a closed loop in this electric field can generate current. So, if a whole conductor is placed in this electric field, will it generate a current in the same direction as the current in the closed loop? The answer is yes. The surface of the conductor will be equivalent to countless extremely fine closed loops that spontaneously form, and current flows through them. This is eddy current. According to the principle of electromagnetic induction, the direction of the current of the eddy current will be the direction that can generate a magnetic field that hinders the change of magnetic flux. At the same time, according to the description of the mutual induction phenomenon above, the magnetic field generated by the eddy current will generate an induced electromotive force in the excitation coil, thereby affecting the current in the excitation coil. Therefore, by monitoring the current signal in the coil, the eddy current can be monitored. When the conductor generating the eddy current changes (such as material, surface defects, etc.), the eddy current will change, the induced electromotive force of the excitation coil will also change, and its current signal will also change accordingly. Therefore, simply by detecting changes in the electrical signal in the coil, surface defects in the material can be discovered, achieving the purpose of nondestructive testing. Alternating current is an electric current whose direction and magnitude change according to a certain periodic law. The current used in daily life is also an alternating current. According to the principle of electromagnetic induction, it can undoubtedly generate a periodically changing magnetic field. This magnetic field can stimulate an electric field in space, and as mentioned above, it can achieve the purpose of detection.

[0033] The inspection target in this application is an engine compressor blade. Disassembly inspection is generally not performed during maintenance, so the available inspection methods are limited. Common nondestructive testing methods in aviation maintenance include ultrasonic, magnetic particle, eddy current, radiographic, and penetrant testing. For this type of surface fatigue crack, magnetic particle, eddy current, and penetrant testing are the primary methods.

[0034] However, magnetic particle testing relies on the leakage magnetic field at the defect site to attract magnetic particles and form magnetic traces to determine whether there are defects on the surface and near-surface of the workpiece. This is difficult to implement without disassembling the blade. Penetrant testing has high requirements for the surface of the object being tested. It must be relatively smooth and free of contamination, and the surface of the object being tested must be pretreated before testing. This method is limited to detecting discontinuities in surface openings and is easily affected by temperature. The procedure is complex and has poor repeatability, making it unsuitable for use. Eddy current testing is a non-destructive testing method based on the principle of electromagnetic induction. This method does not require any surface pretreatment of the object being tested, does not require the application of coupling agents, and can also achieve non-contact rapid testing, so it can be conveniently and quickly tested without disassembly. Eddy current testing is also particularly suitable for detecting discontinuities on the surface and near-surface defects of metal components. Therefore, considering the reliability and feasibility of detection, eddy current testing is the best choice.

[0035] A specific non-destructive testing device for engine compressor blades provided in an embodiment of the present application is described below with reference to the accompanying drawings.

[0036] like Figure 1 and Figure 2 As shown, the engine compressor blade nondestructive testing device provided in the embodiment of the present application includes: a connecting rod 1, one end of the connecting rod 1 is connected to a probe 2, and a handle 3 is provided on the rod body of the connecting rod 1. The handle 3 can slide on the rod body, and the probe 2 can prevent the handle 3 from sliding out;

[0037] The probe 2 includes a detection coil for detecting whether the current signal in the coil changes.

[0038] The working principle of the nondestructive testing device for engine compressor blades is as follows: because when inspecting the compressor in the field, the blades can only be inspected through the inspection hole on the engine casing, so the nondestructive testing device for engine compressor blades is designed to be a structure of probe 2 + slender connecting rod 1 + handle 3. And the distance between blades of the same level is limited, which requires the size of probe 2 to be small enough so that it can enter the inspection hole and be operated flexibly. After experimental calculations, the overall dimensions of the nondestructive testing device for engine compressor blades designed in this application are as follows: the length of connecting rod 1 is 300mm, the handle 3 is 130mm, and the probe 2 is 15*15*20mm 3 In this application, the connecting rod 1 and handle 3 are designed based on practical needs, taking into account factors such as ease of use and grip comfort. They are tubular structures with dimensions of 300 x 5 and 130 x 10, respectively. The connection between the connecting rod 1 and the handle 3 is designed as a cone with a base diameter of 10mm, a top diameter of 7mm, and a height of 20mm.

[0039] In some embodiments, the probe 2 is provided with a detection surface;

[0040] The detection surface is provided with an oblique groove portion and an oblique angle portion, the oblique groove portion and the oblique angle portion are clamped together, and a spring forms a movable constraint between the oblique groove and the oblique angle portion.

[0041] Understandably, the irregular shape of the blades being tested presents a major challenge in conducting comprehensive inspections: the blade edge and tip are the line-contact inspection areas (hereinafter referred to as Area A), while the blade base and blade back are the surface-contact inspection areas (hereinafter referred to as Area B). Specifically, when inspecting the blade edge and tip, the inspection device moves along a curve, making line contact with the inspection area. However, when inspecting the blade base and blade back, the inspection device makes surface contact with the inspection area, requiring the inspection device to move across the blade surface.

[0042] According to mechanical principles, the degrees of freedom of surface contact are smaller than those of line contact. To enable probe 2 to move along a specific trajectory under manual control, its structural degrees of freedom should be constant, and any excess degrees of freedom should be offset by constraints. Therefore, the constraints of probe 2 in the inspection device for areas A and B should differ. Specifically, the probe 2 for area A should have one more structural constraint than the probe 2 for area B.

[0043] Therefore, the present application installs a movable restraint on the detection surface of the probe 2. This restraint utilizes an oblique groove and an oblique angle, and is tightened by a spring to firmly fix it on the detection surface of the probe 2. It can also be easily removed and placed in a placement slot on the rear side of the probe 2. When the probe 2 is used to detect the test area A, the movable restraint is installed. When the probe 2 is used to detect the test area B, the movable restraint only needs to be removed and placed in the placement slot.

[0044] In order to verify the detection effect of the detection device, the blades in the laboratory were used as the detection objects and tested with the detection device. There were simulated crack defects on the blades. The experiment proved that the detection device could successfully detect the cracks. The detection device was sensitive and had good detection effect, which met the design requirements.

[0045] In some embodiments, the detection coil includes a wire and a coil;

[0046] The detection coil adopts an absolute detection coil or a transformer type coil.

[0047] The design parameters of the eddy current detection device include wiring method, coil diameter, number of coil turns, wire diameter, coil spacing and detection frequency. These parameters determine the linearity, sensitivity and measurement range of the detection device.

[0048] Preferably, the absolute detection coil includes:

[0049] The excitation coil and the induction coil are connected in parallel.

[0050] Preferably, the detection coil is provided with

[0051] Magnetic core, used to enhance the magnetic field strength in the detection area.

[0052] Preferably, the detection frequency of the probe 2 is 400kHz to 1800kHz;

[0053] When the AC resistance of the wire is equal to the resistance caused by the proximity effect when only the skin effect is considered at a given frequency, the diameter of the excitation coil wire is 0.08 mm;

[0054] The diameter of the coil is approximately 1.2 times the diameter of the magnetic core;

[0055] The number of turns of the excitation coil is 28 to 35, and the number of turns of the induction coil is 14 to 20;

[0056] The minimum distance between the excitation coil and the induction coil is 3.32 mm.

[0057] The detection frequency of the probe 2 is 1200kHz;

[0058] The number of turns of the excitation coil is 32, and the number of turns of the induction coil is 16.

[0059] The wiring method is determined as follows: Because the blade surface is smooth and free of other interference factors, currently used detection devices primarily employ absolute coil designs. This type of detection coil is suitable for inspecting smooth, flat surfaces that can be brought close to the test. Therefore, the detection device can employ an absolute detection coil, but to improve detection accuracy, a separate excitation coil and response coil are employed. This structure, also known as a transformer-type design, is suitable for inspecting test pieces with smooth, flat surfaces that are easily accessible for inspection. However, transformer-type detection coils are sensitive to lift-off effects, requiring the detection device to remain in close contact with the test piece during inspection, rather than lifting off the surface. Furthermore, transformer-type detection coils, with their separate transmitting and receiving coils, experience less interference on the receiving coil, resulting in a stable signal and the ability to respond to even the smallest differences. Therefore, they are sensitive to surface defects and can accurately and reliably detect cracks on the test surface. Furthermore, because they only require sliding close to the test surface, they offer advantages such as high detection efficiency and flexibility.

[0060] In addition, based on the detection characteristics of blade structure and defects and the need to facilitate in-situ detection, the detection device is designed as a placement type structure, and a magnetic core is installed inside the detection coil to enhance the magnetic field strength in the detection area and improve the detection sensitivity.

[0061] The selection of detection frequency is: According to the eddy current ring theory, calculate the characteristic frequency of the placed coil test piece

[0062]

[0063] Wherein: μ represents magnetic permeability; σ represents electrical conductivity, wherein the electrical conductivity is 97.6% IACS, that is, σ = 56.8MS / m, and the relative magnetic permeability is 1, so the operating frequency is determined as: f1 = (10~50)fg = (10~50) × 99739.

[0064] Due to stress concentration, fatigue cracks are easily generated at the blade edge, blade basin, and 1 / 3 to 1 / 2 of the blade height on the blade back under the action of long-term alternating loads. The crack defects generally penetrate the blade thickness, that is, the effective penetration depth d = 0.5 to 1.5 mm = 2.6y (y is the standard penetration depth, and 2.6 times the standard penetration depth is usually defined as the effective penetration depth in engineering).

[0065]

[0066] Where y represents the crack depth; f represents the test frequency. The operating frequency f2 is determined to be 1338.220446 kHz. The test frequency f is determined by comprehensive analysis of f1 and f2. Calculation shows that the test frequency f ranges from 400 kHz to 1800 kHz. Based on the experiments, a test frequency of 1200 kHz was selected.

[0067] The selection of wire diameter is as follows: for a certain excitation frequency, there is an optimal wire diameter. When only the skin effect is considered, the coil loss decreases as the wire diameter d0 increases. However, when the wire diameter d0 increases, the AC resistance generated by the proximity effect also increases. The relationship between the wire AC resistance and the wire diameter can be seen in Figure 3 Among them, R F is the AC resistance of the conductor at a given frequency when only the skin effect is considered, R G is the resistance caused by the proximity effect. F =R G The AC resistance of the wire is the smallest when . Calculation shows that the optimal diameter of the excitation coil wire is 0.08 mm.

[0068] The determination of the coil diameter is as follows: The determination of the coil diameter mainly considers the following factors: (1) The larger the diameter of the coil, the larger the sensitive range and the larger the linear range. The linear range is generally 1 / 3 to 1 / 5 of the outer diameter of the coil; (2) The larger the diameter of the coil, the lower the sensitivity; (3) The thinner the coil, the higher the sensitivity; (4) The larger the diameter of the coil, the larger the effective range, which is generally three times the diameter of the magnetic core.

[0069] According to the above analysis factors, based on the requirements of detection sensitivity and linear range, the diameter of the magnetic core (made of manganese zinc) is selected to be 1 mm, that is, the inner diameter of the coil is 1 mm and the outer diameter R is about 1.16 mm.

[0070] The number of coil turns is determined based on the eddy current instrument used in aviation maintenance. The impedance range is (1-2) KΩ. L =2πfl, the inductance L can be calculated. The number of turns of the coil can be estimated by the following formula:

[0071]

[0072] Where: L—inductance; цs—effective permeability of the core; N—number of coil turns; l—coil length; and D0—average coil diameter. Calculations show that N ranges from 28 to 35 turns for the excitation coil and 14 to 20 turns for the receiving coil. Experiments show that the excitation coil has 32 turns and the receiving coil has 16 turns.

[0073] The coil spacing is determined as follows: The detection coils primarily use two adjacent coils to simultaneously test adjacent areas of the same specimen. Due to the special structure of engine compressor blades and the tendency for cracks to appear near variable cross-sections, the spacing between the two coils significantly impacts the test results. A larger spacing significantly impacts the variable cross-section; a smaller spacing results in interference between the magnetic fields of the two coils. Therefore, the spacing between the two coils should be kept small, provided that the magnetic fields of the two coils do not interfere with each other. For a coil with an outer diameter of R = 1.16mm, the effective range of a single coil's magnetic field is 3.32mm in diameter. For a radius of 1.66mm, the minimum distance between the two coils for non-interference is 3.32mm.

[0074] In summary, the present invention provides a nondestructive testing device for engine compressor blades, comprising a connecting rod, one end of which is connected to a probe and a handle is provided on the shaft of the connecting rod. The handle can slide on the shaft, and the probe can prevent the handle from sliding out. The probe includes a detection coil for detecting whether the current signal in the coil changes. The nondestructive testing device for engine compressor blades provided by the present invention does not require any surface pretreatment of the object to be tested, does not require the application of coupling agents, and achieves non-contact rapid testing by providing a connecting rod, a probe, and a handle. It can also perform convenient and quick testing without disassembly, and successfully detect cracks. The nondestructive testing device for engine compressor blades provided by the present application is sensitive and has a good detection effect.

[0075] It can be understood that the device embodiment provided above corresponds to the device embodiment described above, and the corresponding specific contents can be referenced to each other and will not be repeated here.

[0076] Those skilled in the art will appreciate that the embodiments of the present application may be provided as devices, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage and optical storage, etc.) containing computer-usable program code.

[0077] The present application is described with reference to the flowcharts and / or block diagrams of the apparatus, device (system), and computer program product according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0078] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0079] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0080] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A nondestructive testing device for engine compressor blades, characterized in that: include: A connecting rod, one end of which is connected to the probe and a handle is provided on the connecting rod body. The handle can slide on the rod body, and the probe can prevent the handle from sliding out. The probe includes a detection coil for detecting whether the current signal in the coil changes; The probe is provided with a detection surface; The detection surface is provided with an oblique groove portion and an oblique angle portion, the oblique groove portion and the oblique angle portion are clamped together, and a spring forms a movable constraint between the oblique groove and the oblique angle portion; A slot is provided on the rear side of the probe for placing the movable constraint.

2. The device according to claim 1, characterized in that The detection coil includes a wire and a coil; The detection coil adopts an absolute detection coil or a transformer type coil.

3. The device according to claim 2, characterized in that The absolute detection coil comprises: The excitation coil and the induction coil are connected in parallel.

4. The device according to claim 3, characterized in that The detection coil is provided with Magnetic core, used to enhance the magnetic field strength in the detection area.

5. The device according to claim 4, characterized in that The detection frequency of the probe is 400kHz to 1800kHz; When the AC resistance of the wire is equal to the resistance caused by the proximity effect when only the skin effect is considered at a given frequency, the diameter of the excitation coil wire is 0.08 mm; The diameter of the coil is 1.2 times the diameter of the magnetic core; The number of turns of the excitation coil is 28 to 35, and the number of turns of the induction coil is 14 to 20; The minimum distance between the excitation coil and the induction coil is 3.32 mm.

6. The device according to claim 5, characterized in that The detection frequency of the probe is 1200kHz; The number of turns of the excitation coil is 32, and the number of turns of the induction coil is 16.

7. The device according to any one of claims 1 to 6, characterized in that include: The length of the connecting rod is 300 mm; The length of the handle is 130 mm; The volume of the probe is 15*15*20mm 3 .

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