CN209992434U - Airplane riveting structure defect automatic detection device based on far-field eddy current - Google Patents

Abstract

The utility model discloses an aircraft riveted structure defect automatic checkout device based on far field vortex, its constitution includes: the device comprises a driving module (1), a direction module (2), a steering engine module (3), a position module (4), a camera module (5), a lifting mechanism (6), a multi-way switch (7), a single chip microcomputer (8), a microprocessor (9), a remote communication module (10), a display (11), a signal conditioning circuit (12), a far field eddy current probe (13), a signal generation module (14), a remote controller (15) and a power supply (16). The single chip microcomputer (8) controls the driving module (1), the direction module (2), the steering engine module (3), the position module (4), the camera module (5) and the lifting mechanism (6) and is connected with the remote communication module (10), and the microprocessor (9) is a control core of the automatic detection device. Thereby providing a new way for quantitative and nondestructive detection of the defects of the multilayer riveting structure of the airplane body.

Description

Airplane riveting structure defect automatic detection device based on far-field eddy current

Technical Field

The utility model belongs to the technical field of the electromagnetism nondestructive test, especially, relate to magnetic memory automatic checkout device that aircraft riveting structure defect detected.

Background

Due to the special working environment, the riveting structure of the airplane body can bear huge stress, so that fatigue cracks are easily generated in the structure, and serious hidden danger is brought to flight safety. How to realize the detection of the defects in the riveting structure is a difficult problem in the field of nondestructive detection.

The traditional nondestructive detection technology is difficult to detect internal defects from the outside of the airplane structure, ultrasonic detection cannot penetrate through a multilayer structure, and detection signals of an acoustic emission technology are easily interfered. GMR-based non-destructive detection methods are highly accurate, but the instrument cost is expensive.

The traditional eddy current inspection, including the pulsed eddy current inspection technology, is inevitably influenced by the skin effect, so that the detection capability of the traditional eddy current inspection technology on deep defects is limited. The magnetic flux leakage technology is only used for detecting ferromagnetic materials, and is difficult to detect non-magnetic components in the aircraft structure.

By using the research results of relevant scholars at home and abroad for reference, the shielding structure is additionally arranged on the exciting coil, so that the propagation of the direct coupling component of the magnetic field is effectively blocked, the probe realizes the far-field detection effect on the defects of the riveting structure, and a new way is provided for the quantitative nondestructive detection of the defects of the multilayer riveting structure of the airplane body.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to realize the combination with long-range eddy current technique and automation mechanized technique, provide an automatic magnetic memory detection device's of aircraft riveted structure technical scheme. The airplane riveting structure defect automatic detection device based on the far-field eddy current is realized.

The technical scheme of the utility model as follows:

the utility model provides an aircraft riveted structure defect automatic checkout device based on far field vortex, its constitution includes: the device comprises a driving module 1, a direction module 2, a steering engine module 3, a position module 4, a camera module 5, a lifting mechanism 6, a multi-way switch 7, a single chip microcomputer 8, a microprocessor 9, a remote communication module 10, a display 11, a signal conditioning circuit 12, a far-field eddy current probe 13, a signal generating module 14, a remote controller 15 and a power supply 16. The single chip microcomputer 8 controls the driving module 1, the direction module 2, the steering engine module 3, the position module 4, the camera module 5 and the lifting mechanism 6 and is connected with the remote communication module 10, the microprocessor 9 is a control core of the automatic detection device and is connected with the single chip microcomputer 8, the signal conditioning circuit 12 and the display 14, the signal conditioning circuit 12 is connected with the far field eddy current probe 13, the far field eddy current probe 13 is connected with the signal generation module 14, and the whole automatic detection device of signals is operated by the remote controller 15.

The far-field eddy current probe 13 comprises the following components: the device comprises a shielding cover, an exciting coil, a detection coil and a riveting structure flat plate.

The excitation coil is located directly over the rivet hole, the excitation coil height is 6mm, thickness is 2mm, the internal diameter is 6mm, the external diameter is 8mm, the number of turns is 200 circles.

The height of the detection coil is 2mm, the thickness is 1mm, the inner diameter is 0.5mm, the outer diameter is 1.5mm, and the number of turns is 800 turns.

The length is 120mm, the width is 120mm, the total thickness is 4mm, and the material to be detected is aluminum.

And a shielding cover is additionally arranged outside the exciting coil.

The shielding cover is composed of three layers of ferromagnetic shielding structures.

The technical effects of the utility model are as follows:

the automatic detection device solves the problem of effectiveness of a measurement area which cannot be reached manually. The application of the method in the airplane detection system improves the airplane detection efficiency, solves the bottleneck that the high-altitude and narrow-field detection cannot be performed in the airplane detection work, and is a major breakthrough in the airplane detection industry.

The far-field eddy current detection technology is a novel electromagnetic nondestructive detection technology, so that the far-field eddy current probe realizes the far-field detection effect on the defects of the riveting structure, and a new way is provided for the quantitative nondestructive detection of the defects of the multilayer riveting structure of the airplane body.

Drawings

FIG. 1 is a schematic diagram of an automatic detecting apparatus for detecting a defect in a riveted structure of an aircraft.

FIG. 2 is a far field eddy current probe configuration diagram.

Fig. 3 is a circuit diagram of signal conditioning.

Fig. 4 a signal generating circuit.

In the figure: the device comprises a driving module 1, a direction module 2, a steering engine module 3, a position module 4, a camera module 5, a lifting mechanism 6, a multi-way switch 7, a single chip microcomputer 8, a microprocessor 9, a remote communication module 10, a display 11, a signal conditioning circuit 12, a far-field eddy current probe 13, a signal generating module 14, a remote controller 15 and a power supply 16.

Detailed Description

The following description will further describe embodiments of the present invention with reference to the accompanying drawings.

1. Integral structure of automatic detection device

The utility model provides an aircraft riveted structure defect automatic checkout device based on far field vortex, its constitution includes: the device comprises a driving module 1, a direction module 2, a steering engine module 3, a position module 4, a camera module 5, a lifting mechanism 6, a multi-way switch 7, a single chip microcomputer 8, a microprocessor 9, a remote communication module 10, a display 11, a signal conditioning circuit 12, a far-field eddy current probe 13, a signal generating module 14, a remote controller 15 and a power supply 16. The single chip microcomputer 8 controls the driving module 1, the direction module 2, the steering engine module 3, the position module 4, the camera module 5 and the lifting mechanism 6 and is connected with the remote communication module 10, the microprocessor 9 is a control core of the automatic detection device and is connected with the single chip microcomputer 8, the signal conditioning circuit 12 and the display 14, the signal conditioning circuit 12 is connected with the far field eddy current probe 13, the far field eddy current probe 13 is connected with the signal generation module 14, and the whole automatic detection device of signals is operated by a remote controller (15) as shown in figure 1.

The far-field eddy current probe 13 comprises the following components: the shield, excitation coil, detection coil, and rivet structure plate are shown in fig. 2.

The excitation coil is located directly over the rivet hole, the excitation coil height is 6mm, thickness is 2mm, the internal diameter is 6mm, the external diameter is 8mm, the number of turns is 200 circles.

The height of the detection coil is 2mm, the thickness is 1mm, the inner diameter is 0.5mm, the outer diameter is 1.5mm, and the number of turns is 800 turns.

The length is 120mm, the width is 120mm, the total thickness is 4mm, and the material to be detected is aluminum.

And a shielding cover is additionally arranged outside the exciting coil.

The shielding cover is composed of three layers of ferromagnetic shielding structures.

2. Far field eddy current probe

(1) Eddy current probe

The traditional far-field eddy current sensor consists of an excitation coil and a detection coil, and a distance of 2 to 3 pipe diameters is generally kept between the excitation coil and the detection coil. The signal generated by the excitation coil can be divided into two parts. One part is transmitted in the pipe and called direct coupling component, and the other part penetrates through the pipe wall and is transmitted forward along the outside of the pipe wall under the gathering action of the pipe wall and called indirect coupling component. The direct coupling component is rapidly attenuated by the induced eddy currents on the tube wall, and the indirect coupling component is attenuated slowly by propagation in air.

In the near field area, the direct coupling component is stronger than the indirect coupling component and passes out of the tube; in the far-field region, the indirect coupling component is stronger than the direct coupling component and thus it propagates inward again through the tube wall, a phenomenon known as "double penetration". By placing the detection coil in the far-field region, the defect information caused by the penetration of indirect coupling components through the tube wall can be extracted.

(2) Signal conditioning circuit optimization design

The detection signal is firstly pre-amplified by a shielding pre-amplifying circuit arranged in the tube, then is sent to a combined filter bank (anti-aliasing band-pass filter-MAX 294 low-pass filter-state reconstruction band-pass filter) through a twisted pair, and finally is sent to the orthogonal locking amplifying circuit shown in figure 3 after passing through an AD620 main amplifying circuit.

Unlike the normal LIA, the quadrature LIA requires two phase sensitive detectors. After passing through a signal channel, a measured signal is respectively input into two different phase sensitive detectors, wherein a reference signal of one phase sensitive detector is theta, the other phase sensitive detector is theta +90 degrees, and the output of the signal after passing through a low-pass filter is in-phase output and quadrature output respectively.

(3) Signal generating circuit

The excitation circuit for far-field eddy current detection can be functionally divided into three parts, namely a single chip circuit, a drive circuit and a switch circuit of an H-bridge, and a high voltage generation circuit. Wherein, the system requires to output a sinusoidal signal with two ends of 80V, the high voltage of 80V can be directly provided by the existing DC-DC power module, which can convert the +200V working voltage provided by the logging system into +80V DC voltage to be supplied to the H-bridge circuit, and input the driving coil under the control of the H-bridge, so the high voltage generating circuit will not be described below.

The single chip microcomputer PIC16F876A has a simple structure and stable performance, and can normally work at high temperature for a long time. The programmed program is burnt into the single chip microcomputer through a J2 serial port, the program starts to work after receiving a high-level signal from the control module through an RC7 pin, a continuous square wave with a certain pulse width is generated through the SPWM wave module, then the pulse width of a PWM wave signal is modulated by a sine wave with the frequency of 20Hz, the series of rectangular pulse waveforms with sine wave regular change, equal amplitude and unequal width are called SPWM waves and can be equivalent to sine waves, and the rectangular pulse waveforms are synthesized and output through RC0, RC1 and RC2 pins.

The design of the PIC16F876A minimal system includes system power, clock management, JTAG online emulation, program download and reset circuitry, and is specifically designed as shown in FIG. 4.

3. Drive module

The driving module provides power for the automatic scanning of the detection device in the airplane riveting structure, and the driving device of the system adopts two direct current motors. In order to meet the requirement of large-scale scanning of the riveting structure of the airplane and realize the change of the track of the detection device, the two direct current motors are required to be driven by differential speed to realize the flexible steering function of the detection device. The two direct current motors realize the wide-range regulation of the rotating speed through PWM speed regulation, and the steering control of the motors is realized by adopting the speed difference of the two driving wheels. And two photoelectric encoders are adopted to respectively acquire the rotating speeds of the two driving wheels as the feedback of speed control.

(1) Driving motor

The reasonable motor selection can not only influence the size and the structural arrangement of the detection device, but also play a key role in the movement flexibility of the moving mechanism of the detection device. The driving motor adopts a direct current motor and a stepping motor with better speed regulation performance.

The direct current motor has smaller rotational inertia, better control characteristic and higher response speed, and can meet the sensitivity requirement of a detection device; the speed adjusting range is wide, and the requirement of the detection device on rapidity can be met; the low-speed stability performance is good, and the stability requirement of the moving mechanism can be met; the mechanical property is hard, the overload capacity is stronger, and the requirement of carrying objects of the detection device can be met.

The stepping motor can directly realize digital control, has better control performance, can be quickly started, braked and reversely rotated, also has stronger interference resistance, and does not have the accumulated error of angular displacement or linear displacement. However, the starting frequency is too high, resonance is generated when the control is not proper, a relatively large rotating torque is difficult to obtain, a relatively high rotating speed is difficult to obtain, and overload capacity is generally absent.

(2) Driving wheel

The driving wheel provides driving force for the detection device. In order to meet the detection requirement of the riveting structure of the airplane, the driving wheel has anti-corrosion performance. The driving module of the detection device is two direct current motors, in order to enable the detection device to be compact in structure, the two direct current motors are vertically placed, the direct current motors are fixedly connected with the upper panel of the detection device through the speed reducer through bolts, the output shaft of the speed reducer is driven by a pair of straight-tooth bevel gears to transmit power to the driving shaft, and the driving shaft drives the driving wheel to rotate. An aluminium alloy was chosen as the material for the driving wheel, which had a diameter of 96mm and a width of 25 mm. Since the detecting device mainly relies on the difference in the rotational speed of the drive to effect steering, the drive wheels can be severely worn. In order to reduce the abrasion of the driving wheels and avoid the slipping phenomenon between the driving wheels and the airplane riveting structure, a circle of rubber with the thickness of 2mm is sleeved on the excircle of each of the two driving wheels, so that the friction force between the driving wheels and the bottom plate is increased.

4. Position module

The position module is one of the key parts of the detection device and is used for determining the accurate position of the defect on the airplane riveting structure. The designed positioning device consists of an encoder and a laser distance sensor, so that the two-dimensional position of the defect on the airplane riveting structure can be determined. The working principle is as follows: in the process of detecting the aircraft riveting structure, the driving wheel drives the photoelectric encoder to synchronously rotate, when the magnetic flux leakage detection probe moves one sampling interval per time relative to the aircraft riveting structure, the pulse encoder can generate a TTL electric pulse, the data acquisition module is triggered, and all 24 channels are acquired once. The number of samples times the distance traveled by the sensing device within a sampling interval is its longitudinal coordinate. The laser range sensor can measure the distance of the defect from the reference object, so that its transverse coordinates can be determined.

5. Lifting mechanism

The lifting mechanism mainly comprises: lead screw motor, support, bracing piece and magnetization unit. A support in the lifting module of the detection device is fixed with a screw rod motor top cap bolt, a support rod is connected with the detection device through a bolt, and the support rod is fastened with the support bolt. When the welding seam passes, the screw rod motor rotates forwards to drive the detection device to ascend, and the screw rod motor rotates backwards after the welding seam to enable the detection device to descend to a required position.

6. Direction module

Because this device adopts the laser positioning mode, so adopt two laser rangefinder sensors that contained angle is adjustable to carry out the direction detection, can record the skew direction of planning the route of detection device to can in time make the adjustment. The distance between the detection device and a reference object is measured through the laser ranging sensor, and the position of the detection device on the airplane riveting structure can be obtained by matching the information collected by the encoder. The SKD system laser distance sensor is selected, so that the method has the remarkable advantages of accuracy and rapidness in measurement, long distance, non-contact and the like, and in the airplane riveting structure, the brightness of laser exceeds the brightness of the surrounding environment, and the measuring range can be increased.

The device adopts an RS232 serial port data output mode. The MC9S12XS128 singlechip is provided with two enhanced serial communication ports, and an RS-232 driving circuit of the serial port can realize the level conversion between TTL level and RS-232 level, so that the singlechip and the laser ranging sensor can conveniently carry out serial communication. Level conversion is performed using an RS232 standard MAX232 chip that contains two drivers, two receivers and a voltage generator circuit to provide the TLA/ELA-232-F level. Each receiver converts the TLA/ELA-232-F level into a 5V TTL/CMOS level to send the signal measured by the laser ranging sensor to the single chip, and the interface circuit is shown in fig. 3.

7. Steering engine module

The information obtained when the automatic detection device is driven on the aircraft riveting structure is originated from the CCD sensor. The CCD, i.e., a charge coupled device, can convert an optical image into a digital signal. And the digital signals obtained from the CCD sensor are synchronously separated by an LM1881 video synchronous separation chip to obtain required video image signals. The separated signal obtained from LM1881 also does not directly reflect information about the riveted structure of the aircraft.

8. Camera module

Recognizing a riveting structure of the airplane: a CCD sensor is used.

CCD is a charge coupled device, which is a detecting element that uses charge to express signal size and uses coupling mode to transmit signal, and has the advantages of self-scanning, wide sensing spectrum range, small distortion, small volume, light weight, low system noise, low power consumption, long service life, high reliability, etc., and can be made into a very high integration level assembly. A Charge Coupled Device (CCD) is a new type of semiconductor device developed in the early 70 s of the 20 th century.

With the continuous development of the CCD technology and theory, the application range and depth of the CCD technology are necessarily larger and larger. The CCD is integrated by using a high-sensitivity semiconductor material, and can produce correspondent charge signal according to the light irradiated on its surface, and can be converted into "0" or "1" digital signal by means of A/D converter chip, and after the digital signal is undergone the processes of compression and program arrangement, the digital signal can be stored in flash memory or hard disk card, i.e. the light-receiving signal can be converted into electronic image signal which can be recognized by computer, so that it can accurately measure and analyze the measured object.

9. Single chip microcomputer

An 8-bit singlechip is selected.

The single chip computer (Microcontrollers) is an integrated circuit chip, and is a small and perfect microcomputer system formed by integrating the functions of a central processing unit CPU with data processing capacity, a random access memory RAM, a read only memory ROM, various I/O ports, an interrupt system, a timer/counter and the like (possibly including a display drive circuit, a pulse width modulation circuit, an analog multiplexer, an A/D converter and the like) on a silicon chip by adopting a super-large scale integrated circuit technology, and is widely applied to the field of industrial control. 8-bit single chip microcomputer, developed to the current 300M high-speed single chip microcomputer.

While the anti-interference capability of a hardware system is improved, the software anti-interference is more and more emphasized due to the flexible design, hardware resource saving and good reliability.

10. Microprocessor

The microprocessor selects the DSP chip.

The DSP chip adopts a Harvard structure with separated programs and data, is provided with a special hardware multiplier, widely adopts pipeline operation, provides special DSP instructions, and can be used for quickly realizing various digital signal processing algorithms.

Classified according to the data format in which the DSP chip operates. DSP chips with data working in fixed-point format are called fixed-point DSP chips, such as TMS320C1X/C2X, TMS320C2XX/C5X, TMS320C54X/C62XX series of TI company, ADSP21XX series of AD company, DSP16/16A of AT & T company, MC56000 of Motolora company, and the like. The chips called floating point DSP, which operate in floating point format, such as TMS320C3X/C4X/C8X from TI, ADSP21XXX series from AD, DSP32/32C from AT & T, MC96002 from Motolora, etc.

11. Power supply module

Since the detection device is mobile, a portable battery is used to provide a reliable operating voltage for the entire detection device. Currently, the common rechargeable batteries are: nickel-cadmium batteries, nickel-hydrogen batteries, lithium batteries, lead-acid batteries, and the like. The advantages and the disadvantages of various batteries are comprehensively considered, and the power supply requirements of the whole device, including a motor, a driver, a sensor and the like, are analyzed in combination with the design scheme requirements of a control module, and the current of about 8A is probably required. Considering the performance, current, weight and other factors of the battery, a 24V and 10A lithium battery is selected as a power source.

In whole detecting system, the operating voltage diverse that circuit module difference place needs to provide, two direct current motor need directly use 24V mains operated, and plug-type electro-magnet needs 24V voltage, and motor drive needs 24V voltage, and single chip microcomputer system needs 5V voltage, and laser range finding sensor and rotary encoder operating voltage are 5V.

12. Remote control device

In the remote control transmitting circuit, there are two kinds of circuits, i.e., an encoder and a 38kHz carrier signal generator. In the application circuit without multiplex control, the infrared remote control transmitting and receiving circuit with less circuits can be formed by using the conventional integrated circuit, and the circuit does not need to use a more complex special codec, so the manufacture is easy.

Claims (7)

1. The utility model provides an aircraft riveted structure defect automatic checkout device based on far field vortex, its constitution includes: drive module (1), direction module (2), steering wheel module (3), position module (4), camera module (5), rising mechanism (6), multi-way switch (7), singlechip (8), microprocessor (9), remote communication module (10), display (11), signal conditioning circuit (12), far field eddy current probe (13), signal generation module (14), remote controller (15), power (16), its characterized in that: singlechip (8) control drive module (1), direction module (2), steering wheel module (3), position module (4), camera module (5) and rising mechanism (6), and be connected with remote communication module (10), microprocessor (9) are automatic checkout device's control core, with singlechip (8), signal conditioning circuit (12) and display (11) are connected, signal conditioning circuit (12) are connected with far field eddy current probe (13), far field eddy current probe (13) are connected with signal generation module (14), whole automatic checkout device is operated by remote controller (15).

2. The automatic detection device for the defects of the airplane riveting structure according to claim 1, characterized in that: the far-field eddy current probe (13) comprises the following components: the device comprises a shielding cover, an exciting coil, a detection coil and a riveting structure flat plate.

3. The automatic detection device for the defects of the airplane riveting structure according to claim 2, characterized in that: the excitation coil is located directly over the rivet hole, the excitation coil height is 6mm, thickness is 2mm, the internal diameter is 6mm, the external diameter is 8mm, the number of turns is 200 circles.

4. The automatic detection device for the defects of the airplane riveting structure according to claim 2, characterized in that: the height of the detection coil is 2mm, the thickness is 1mm, the inner diameter is 0.5mm, the outer diameter is 1.5mm, and the number of turns is 800 turns.

5. The automatic detection device for the defects of the airplane riveting structure according to claim 2, characterized in that: the length is 120mm, the width is 120mm, the total thickness is 4mm, and the material to be detected is aluminum.

6. An aircraft riveting structure defect automatic detection device according to claim 2 or 3, characterized in that: and a shielding cover is additionally arranged outside the exciting coil.

7. The automatic detection device for the defects of the airplane riveting structure according to claim 2, characterized in that: the shielding cover is composed of three layers of ferromagnetic shielding structures.

Images