CN212482677U - Device for detecting natural frequency of object by adopting laser excitation - Google Patents
Device for detecting natural frequency of object by adopting laser excitation Download PDFInfo
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- CN212482677U CN212482677U CN202021551612.7U CN202021551612U CN212482677U CN 212482677 U CN212482677 U CN 212482677U CN 202021551612 U CN202021551612 U CN 202021551612U CN 212482677 U CN212482677 U CN 212482677U
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Abstract
The utility model discloses a device for detecting the natural frequency of an object by adopting laser excitation, which comprises a laser transmitter for inducing the vibration of the object to be detected, an optical fiber vibration meter for detecting the vibration frequency of the object, an oscilloscope connected with the optical fiber vibration meter and a placing platform; the placing table is provided with a placing position for placing an object to be tested, and the bottom of the placing position is provided with a small hole for accommodating laser emitted by the laser emitter to pass through; the optical fiber vibration meter comprises an optical fiber probe and a signal conversion analyzer, and the signal conversion analyzer is connected with an oscilloscope; the optical fiber probe is used for collecting vibration signals of an object and is positioned above the mounting position; the signal conversion analyzer is connected with the optical fiber probe and is used for converting and analyzing the vibration signal; the oscilloscope is used for displaying vibration information. The device has the characteristics of simple operation, no limitation of the application range by the material of the object to be detected and high accuracy.
Description
Technical Field
The utility model relates to a vibration detection technical field, in particular to adopt laser excitation to detect device of object natural frequency.
Background
In the traditional industrial production, an impedance analyzer is generally used for testing the natural frequency of an object, the measurement method is that after the object is produced and formed, the object needs to be subjected to a series of pretreatment before measurement, for example, some objects need to pass through a sticky piezoelectric ceramic sheet firstly, the impedance analyzer can be placed into the object for measurement after an electrode is welded, and after the measurement is finished, accessories attached to the surface of the object need to be removed. Some objects, which do not require such pre-treatment, are placed in the impedance analyzer and held by a clamp for connection to the analyzer. The above method for measuring the natural frequency of an object by using an impedance analyzer has the following disadvantages:
1. the process is complicated, and the efficiency is low: some objects put into the impedance analyzer need to be preprocessed, for example, piezoelectric patches are pasted on the objects firstly, and the measurement can be carried out only after electrodes are welded.
2. The applicable scope is smaller: the vibration measuring device can only measure objects with conductivity, such as metal and piezoelectric materials, and the applicable range is small.
3. Damage object, measurement deviation: the natural frequency of an object is tested by adopting an impedance analyzer, a piezoelectric sheet and a welding electrode need to be pasted or the object needs to be clamped by a clamp, the attachment pieces can damage the object to be measured, and certain influence can be generated on the natural frequency of the object to be measured, so that certain deviation is generated on the measuring result.
In view of the above, the present invention provides an apparatus for detecting the natural frequency of an object by using laser excitation, and the present application is developed accordingly.
Disclosure of Invention
The utility model provides a device for detecting the natural frequency of an object by adopting laser excitation, which has the characteristics of simple operation, no limitation of the application range by the material of the object to be detected and high accuracy; specifically, the utility model discloses a realize through following technical scheme:
a device for detecting the natural frequency of an object by adopting laser excitation comprises a laser transmitter for inducing the vibration of the object to be detected, an optical fiber vibration meter for detecting the vibration frequency of the object, an oscilloscope connected with the optical fiber vibration meter, and a placing table; the placing table is provided with a placing position for placing an object to be tested, and the bottom of the placing position is provided with a small hole for accommodating laser emitted by the laser emitter to pass through; the optical fiber vibration meter comprises an optical fiber probe and a signal conversion analyzer, and the signal conversion analyzer is connected with an oscilloscope; the optical fiber probe is used for collecting vibration signals of an object and is positioned above the mounting position; the signal conversion analyzer is connected with the optical fiber probe and is used for converting and analyzing the vibration signal; the oscilloscope is used for displaying vibration information.
Furthermore, an optical plane mirror is arranged between the laser transmitter and the mounting position of the object to be detected and used for changing the laser transmitting direction so that laser can directly irradiate the mounting position of the object to be detected.
Furthermore, the optical fiber probe is arranged on a spatial displacement device, and the spatial displacement device is used for adjusting the spatial position of the optical fiber probe.
Further, the spatial displacement device includes a vertical direction moving bar and a horizontal direction moving bar.
Furthermore, the vertical direction moving rod and the horizontal direction moving rod are connected through a spiral cross clamp.
Furthermore, a sponge pad is arranged at the installation position of the optical fiber probe and the space displacement device.
Further, the optical fiber probe and the sponge pad are in interference fit.
Further, the fiber optic probe comprises a transmitting fiber and a receiving fiber; the transmitting optical fiber is used for transmitting light, and the light reflected by the object is received by the receiving optical fiber.
Further, the signal conversion analyzer includes a photoelectric conversion element for converting the received optical signal into an electrical signal.
The beneficial effect of this application lies in:
1. convenient operation, it is efficient: meanwhile, the object to be detected can be detected only by placing the object to be detected at the corresponding position, the accessory does not need to be installed in advance, and the accessory does not need to be detached after the detection is finished, so that the detection procedures are reduced, and the efficiency is improved.
2. The application range is large: the laser excitation method utilizes the laser thermo-elastic effect principle, and the object to be detected which can generate the laser thermo-elastic effect can be metal, organic glass, a piezoelectric material, a part of fiber reinforced/laminated composite material and the like, which are industrially applied with more materials, so that the device can be applied to more fields, and has wider range of object detection compared with an impedance analyzer.
3. The object is complete, and the measurement is accurate: this application has adopted laser as the excitation source, does not need extra annex to adhere to and can realize the vibration of object on the object surface that awaits measuring, also need not the centre gripping object, and the overall structure weight of the object that awaits measuring does not change, has guaranteed the accuracy of detection data.
Drawings
Fig. 1 is a perspective view of an embodiment of the present invention.
Wherein: 1. a laser transmitter; 2. an optical fiber vibration meter; 21. a fiber optic probe; 211. an emission optical fiber; 212. receiving an optical fiber; 22. a signal conversion analyzer; 3. an object; 4. a placing table; 41. setting a position; 5. an optical plane mirror; 6. a spatial displacement device; 61. a vertical direction moving bar; 62. a horizontally moving rod; 7. a sponge pad; 8. an oscilloscope.
Detailed Description
The present invention will be further described with reference to the accompanying drawings and the following detailed description.
As shown in fig. 1, the device for detecting the natural frequency of an object 3 by using laser excitation comprises a laser emitter 1 for inducing the object 3 to be detected to vibrate; the vibration measuring device also comprises an optical fiber vibration meter 2 used for detecting the vibration frequency of the object 3 and analyzing to obtain the natural frequency of the object 3; the optical fiber vibration meter 2 is connected with the oscilloscope 8 and displays the detected vibration information; and a placing table 4 for placing the object 3 to be measured.
Because the existing laser transmitter 1 is limited by connecting lines, transmitting ports and the like, the laser transmitter can only transmit laser in the horizontal direction; meanwhile, the object 3 is difficult to clamp, and only the placing position 41 for placing the object 3 on the plane of the placing table 4 can be selected in consideration of the operability of industrial detection, a small hole is formed in the bottom of the placing position 41 and used for accommodating the laser emitted by the laser emitter 1 to pass through, and only the top and the bottom of the object 3 can be irradiated by the laser.
Therefore, in order to enable the horizontally emitted laser to irradiate the object 3 to be measured from the vertical direction, the optical plane mirror 5 is arranged between the laser emitter 1 and the object 3 to be measured, and the angle between the optical plane mirror 5 and the laser irradiation direction is 45 degrees, so that the horizontally emitted laser can rotate by 90 degrees and vertically hit the inner side surface of the object 3.
The laser is reflected by the optical plane mirror 5 and directly irradiates the inner side surface of the object 3, and due to the laser thermo-elastic effect, ultrasonic vibration can be generated at the laser direct-irradiating point on the inner side surface of the object 3. The laser thermo-elastic effect is as follows: when the laser power density irradiated on the structure surface is less than 107W/cm2At this time, the structure is heated by absorbing the energy of laser irradiation, but the absorbed energy hardly sublimates and melts the material, and at this time, the increase in temperature causes the material volume of the object 3 to rapidly expand, causing elastic stress, and this elastic energy propagates in the form of ultrasonic waves in the structure of the object 3, so that the structure of the object 3 irradiated by the laser vibrates.
Therefore, the material of the object 3 that can be measured by the present application needs to have the property of generating the thermo-elastic effect under the laser irradiation, and the material can be selected from metal, organic glass, piezoelectric material, partial fiber reinforced/laminated composite material and the like.
The optical fiber vibration meter 2 comprises an optical fiber probe 21 and a signal conversion analyzer 22 which are connected, wherein the optical fiber probe 21 is positioned above the object to be measured 3, and the signal conversion analyzer 22 is connected with the oscilloscope 8; the use mode is as follows: the optical fiber probe 21 is used for acquiring the vibration frequency of the object 3, transmitting the vibration frequency of the object 3 to the optical fiber probe 21 as an optical signal, analyzing and converting the optical signal into an electric signal through the signal conversion analyzer 22, measuring the vibration signal by measuring the electric signal, reading information such as waveform, frequency, amplitude and the like of the vibration object 3, and displaying the information on the oscilloscope 8 connected with the optical fiber vibration meter 2.
The fiber optic probe 21 comprises a transmitting optical fiber 211 and a receiving optical fiber 212. The emitting optical fiber 211 emits light to the surface of the object 3 perpendicularly, the light is reflected by the surface of the object 3 to the receiving optical fiber 212, and the reflected light signal carries the vibration information of the object 3 to be measured.
The optical fiber probe 21 is installed on the spatial displacement device 6, and the spatial displacement device 6 is used for adjusting the spatial position of the optical fiber probe 21, so that the optical fiber probe 21 vertically points to the surface of the object 3, and controlling the distance between the optical fiber probe 21 and the object 3 to be tested, so that the distance is within the effective test range of the optical fiber probe 21. The space displacement means 6 includes a vertical direction moving rod 61 and a horizontal direction moving rod 62, which are connected by a screw cross clamp. In order to protect the optical fiber probe 21, a sponge pad 7 is arranged at the installation position of the optical fiber probe 21 and the space displacement device 6, and the optical fiber probe 21 and the sponge pad 7 are in interference fit.
The optical fiber probe 21 is connected with a signal conversion analyzer 22, the signal conversion analyzer 22 is connected with an oscilloscope 8, an optical signal received by the optical fiber probe is converted into an electrical signal by a photoelectric conversion element integrated in the signal conversion analyzer 22, the detection of a vibration signal is realized by detecting and analyzing the electrical signal, the waveform and the frequency of the detected vibration signal are displayed by the oscilloscope 8, and the natural frequency of the structure of the object 3 is obtained by analysis; according to the standard of production and acceptance of the object, whether the measuring object 3 is qualified or not is judged by comparing the detected natural frequency with the allowable range of the natural frequency.
Before detecting the natural frequency of the object 3, the zeroing step of the optical fiber probe 21 is first performed, that is, the optical fiber probe 21 is located at the zero point position by adjusting the vertical moving rod 61 and the horizontal moving rod 62.
The zeroing operation is as follows: according to the instruction of the signal conversion analyzer 22, the optical fiber probe 21 is first placed on the surface of the object 3 to be measured and contacted with the object, at this time, the total emitted light quantity of the optical fiber probe 21 is reflected to the emitting optical fiber 211 and is not transmitted to the receiving optical fiber 212, the output signal is 0, the "CAL" key on the measuring instrument is pressed, the optical fiber probe 21 is vertically moved, when the distance between the optical fiber probe 21 and the surface of the object to be measured is increased, the light quantity received by the receiving optical fiber 212 is also increased until the receiving optical fiber 212 is completely illuminated, the "cal.start" key on the measuring instrument is pressed, and the optical fiber probe 21 automatically completes zero setting.
After the zeroing step is completed, the vertical moving rod 61 and the horizontal moving rod 62 are adjusted to place the fiber probe 21 at the measurement position, and the measurement is started. Without re-zeroing, a large number of objects 3 of the same type can be measured.
The device is particularly suitable for detecting products such as transducer shells, and the products such as the transducer shells originally detected need to be placed in an impedance analyzer for the operation of measuring the inherent frequency after piezoelectric ceramic pieces are adhered to the surfaces of the transducer shells and electrodes are welded; the original measuring mode can be changed after the device is adopted, and the shell does not need to be processed in advance due to non-contact measurement, so that the measuring efficiency is increased.
The steps of detecting whether the object 3 is qualified by adopting the device are as follows:
firstly, placing an object 3 to be measured on a placing position 41 of a placing table 4, completing the zeroing step of the optical fiber probe 21, and then adjusting the optical fiber probe 21 to a measuring position; starting a laser transmitter 1 to transmit laser, irradiating on an object 3 to be detected, inducing the object 3 to vibrate according to the laser thermo-elastic effect principle, enabling a transmitting optical fiber 211 in an optical fiber probe 21 to transmit an optical fiber 211 to strike on the vibrating object 3, enabling the object 3 to reflect light to a receiving optical fiber 212, transmitting a vibration signal through an optical signal, enabling the receiving optical fiber 212 to receive the optical signal, converting the received optical signal into an electrical signal through a signal conversion analyzer 22, detecting the vibration signal through detecting and analyzing the electrical signal, displaying the waveform and frequency of the detected vibration signal through an oscilloscope 8, and analyzing to obtain the inherent frequency of the structure of the object 3; screening of the objects 3 is realized by judging whether the detected natural frequency of the objects 3 is within a qualified range.
Above is the utility model discloses preferred embodiment the utility model discloses make a plurality of other simple replacements and changes under the design prerequisite, all should regard as belonging to the utility model discloses a protection category.
Claims (9)
1. A device for detecting the natural frequency of an object by adopting laser excitation is characterized in that: the device comprises a laser transmitter for inducing the vibration of an object to be detected, an optical fiber vibration meter for detecting the vibration frequency of the object, an oscilloscope connected with the optical fiber vibration meter, and a placing table; the placing table is provided with a placing position for placing an object to be tested, and the bottom of the placing position is provided with a small hole for accommodating laser emitted by the laser emitter to pass through; the optical fiber vibration meter comprises an optical fiber probe and a signal conversion analyzer, and the signal conversion analyzer is connected with an oscilloscope; the optical fiber probe is used for collecting vibration signals of an object and is positioned above the mounting position; the signal conversion analyzer is connected with the optical fiber probe and is used for converting and analyzing the vibration signal; the oscilloscope is used for displaying vibration information.
2. The apparatus for detecting the natural frequency of the object by using the laser excitation as claimed in claim 1, wherein: an optical plane mirror is arranged between the laser transmitter and the mounting position of the object to be detected and used for changing the laser transmitting direction so that laser can directly irradiate the mounting position of the object to be detected.
3. The apparatus for detecting the natural frequency of the object by using the laser excitation as claimed in claim 1, wherein: the optical fiber probe is arranged on the spatial displacement device, and the spatial displacement device is used for adjusting the spatial position of the optical fiber probe.
4. The apparatus for detecting the natural frequency of the object by using the laser excitation as claimed in claim 3, wherein: the space displacement device includes a vertical direction moving bar and a horizontal direction moving bar.
5. The apparatus for detecting the natural frequency of the object by using the laser excitation as claimed in claim 4, wherein: the vertical direction moving rod and the horizontal direction moving rod are connected through a spiral cross clamp.
6. The apparatus for detecting the natural frequency of the object by using the laser excitation as claimed in claim 3, wherein: and a sponge gasket is arranged at the installation position of the optical fiber probe and the space displacement device.
7. The apparatus for detecting the natural frequency of the object by using the laser excitation as claimed in claim 6, wherein: the optical fiber probe is in interference fit with the sponge pad.
8. The apparatus for detecting the natural frequency of the object by using the laser excitation as claimed in claim 1, wherein: the optical fiber probe comprises a transmitting optical fiber and a receiving optical fiber; the transmitting optical fiber is used for transmitting light, and the light reflected by the object is received by the receiving optical fiber.
9. The apparatus for detecting the natural frequency of the object by using the laser excitation as claimed in claim 1, wherein: the signal conversion analyzer includes a photoelectric conversion element for converting a received optical signal into an electrical signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021551612.7U CN212482677U (en) | 2020-07-30 | 2020-07-30 | Device for detecting natural frequency of object by adopting laser excitation |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021551612.7U CN212482677U (en) | 2020-07-30 | 2020-07-30 | Device for detecting natural frequency of object by adopting laser excitation |
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| Publication Number | Publication Date |
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| CN212482677U true CN212482677U (en) | 2021-02-05 |
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| CN202021551612.7U Active CN212482677U (en) | 2020-07-30 | 2020-07-30 | Device for detecting natural frequency of object by adopting laser excitation |
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