CN114689564B - Laser rust removal state detection method - Google Patents
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- CN114689564B CN114689564B CN202210324221.9A CN202210324221A CN114689564B CN 114689564 B CN114689564 B CN 114689564B CN 202210324221 A CN202210324221 A CN 202210324221A CN 114689564 B CN114689564 B CN 114689564B
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- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/62—Systems in which the material investigated is excited whereby it emits light or causes a change in wavelength of the incident light
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Abstract
The invention relates to the technical field of laser rust removal, in particular to a laser rust removal state detection method which comprises S1-S5, wherein real-time laser capability temperature, reflected light intensity, surface acoustic wave signals and piezoelectric signals are transmitted to a singlechip for analysis until the four signals completely reach the standard, and rust removal is completed. The invention adopts a plurality of methods for monitoring simultaneously, is convenient for closing the laser power supply in time to stop rust removal, is environment-friendly, prevents metal matrix damage caused by excessive scanning while ensuring rust cleaning force, effectively improves monitoring efficiency and reduces energy consumption.
Description
Technical Field
The invention relates to the technical field of laser rust removal, in particular to a laser rust removal state detection method.
Background
The laser rust removing principle is that laser cleaning is performed, a high-frequency high-energy laser pulse is utilized to irradiate the surface of a workpiece, a coating layer can instantly absorb focused laser energy, oil stains, rust spots or coatings on the surface are instantly evaporated or peeled off, the surface attachments or the cleaning mode of the surface coatings are effectively removed at a high speed, the laser pulse with short action time does not harm a metal substrate under proper parameters, and the rust removing state is detected while laser rust removing is performed, so that damage to the metal substrate is reduced.
Through searching, china patent 201010290349.5 discloses a laser rust removal state detection method and device, the laser rust removal state detection method detects plasma excited in the laser rust removal process, converts plasma energy into voltage signals, compares the difference of output signals of a substrate surface and a rust surface in the laser impact process to detect the rust removal state, the method is simple to realize, has strong anti-interference capability, mainly comprises a focusing lens, a filter, a photoelectric conversion device and a controller, the filter filters reflected light and scattered light with the same wavelength as an impact laser beam, the photoelectric conversion device converts the plasma energy into the voltage signals, and the controller compares and analyzes the voltage signals and determines the rust removal state, but the patent simply adopts piezoelectric signal detection, has poor effect and is easy to cause substrate damage due to excessive scanning. Accordingly, a laser rust removal state detection method is provided by those skilled in the art to solve the problems set forth in the background art.
Disclosure of Invention
The invention aims to provide a laser rust removal state detection method for solving the problems in the background technology.
In order to achieve the above purpose, the present invention provides the following technical solutions: a laser rust removal state detection method comprises the following steps:
s1: aiming at the determined required derusting threshold value and reflected light intensity threshold value of workpieces made of different materials, the energy temperature of laser during laser derusting is monitored in real time;
s2: performing single-point multiple laser irradiation on the rust degree by using laser with the wavelength of 1060-1064nm, the pulse width of 8-10ns, the energy of 1-1.2J and the spot diameter of 2.5-3mm, and sequentially collecting surface acoustic wave signals generated in the rust removing process by using a PVDF piezoelectric film;
s3: collecting light intensity information of the laser-induced plasma by adopting a photodiode, inputting the light intensity information into an oscilloscope, and converting the light intensity information of the laser-induced plasma into a voltage signal;
s4: the method comprises the steps of focusing by adopting a halogen tungsten lamp, projecting the focused halogen tungsten lamp on the surface of a derusting workpiece, reflecting the derusted workpiece to an optical fiber bundle by a focusing mirror, and collecting the derusted workpiece by using red, green and blue light detectors sequentially through a beam splitter;
s5: and transmitting real-time laser capability temperature, surface acoustic wave signals, piezoelectric signals and monitoring data of the red, green and basket photo detectors to the singlechip for analysis until all the four reach the standard, and completing rust removal.
As a further aspect of the present invention: the determination formula of the rust removal threshold in S1 is as follows: t is t v ≤t s ≤t m
Wherein: t is t v Is the vaporization temperature of the rust layer, t s Is the laser energy temperature, t m Is the melting point of the workpiece;
when t v ＝t s The rust removal threshold value of the workpiece is as t s ＝t m And is the damage threshold of the workpiece.
As a further aspect of the present invention: t is t s The following equation is used to obtain:
wherein: f is laser energy density, R is workpiece surface reflectivity, K is thermal conductivity, a is thermal diffusivity, and t is laser pulse width.
As a further aspect of the present invention: and S2, the effective area of the PVDF piezoelectric film is 1.2X3 cm, the thickness of the PVDF piezoelectric film is 50 mu m, and the PVDF piezoelectric film is adhered to the surface of a workpiece through double-sided adhesion.
As a further aspect of the present invention: and S4, the surface acoustic wave signal is changed along with the continuous falling of the rust surface, and the rust removal is successful when the received surface acoustic wave signal is unchanged for 3 times.
As a further aspect of the present invention: and S4, a voltage signal threshold value is stored in the singlechip, and the rust removal is successful by calculating the voltage signal difference value between the front and rear times until the calculated voltage signal difference value is smaller than the voltage signal threshold value.
Compared with the prior art, the invention has the beneficial effects that: the invention adopts a plurality of methods for monitoring simultaneously, is convenient for closing the laser power supply in time to stop rust removal, is environment-friendly, prevents metal matrix damage caused by excessive scanning while ensuring rust cleaning force, effectively improves monitoring efficiency and reduces energy consumption.
Detailed Description
Example 1
In the embodiment of the invention, a laser rust removal state detection method comprises the following steps:
s1: aiming at the determined required derusting threshold value and reflected light intensity threshold value of workpieces made of different materials, the energy temperature of laser during laser derusting is monitored in real time;
s2: laser with the wavelength of 1064nm, the pulse width of 10ns, the energy of 1J and the spot diameter of 3mm is used for carrying out single-point multiple laser irradiation on the rust degree, and a PVDF piezoelectric film is used for sequentially collecting acoustic surface wave signals generated in the rust removal process;
s3: collecting light intensity information of the laser-induced plasma by adopting a photodiode, inputting the light intensity information into an oscilloscope, and converting the light intensity information of the laser-induced plasma into a voltage signal;
s4: the method comprises the steps of focusing by adopting a halogen tungsten lamp, projecting the focused halogen tungsten lamp on the surface of a derusting workpiece, reflecting the derusted workpiece to an optical fiber bundle by a focusing mirror, and collecting the derusted workpiece by using red, green and blue light detectors sequentially through a beam splitter;
s5: and transmitting real-time laser capability temperature, surface acoustic wave signals, piezoelectric signals and monitoring data of the red, green and basket photo detectors to the singlechip for analysis until all the four reach the standard, and completing rust removal.
Further, the determination formula of the rust removal threshold in S1 is: t is t v ≤t s ≤t m
Wherein: t is t v Is the vaporization temperature of the rust layer, t s Is the laser energy temperature, t m Is the melting point of the workpiece;
when t v ＝t s The rust removal threshold value of the workpiece is as t s ＝t m And is the damage threshold of the workpiece.
Further, t s The following equation is used to obtain:
wherein: f is laser energy density, R is workpiece surface reflectivity, K is thermal conductivity, a is thermal diffusivity, and t is laser pulse width.
Further, the effective area of the PVDF piezoelectric film in S2 is 1.2X3 cm, the thickness is 50 μm, and the PVDF piezoelectric film is adhered to the surface of the workpiece through double-sided adhesive.
Further, the surface acoustic wave signal in S4 changes with the continuous falling of the rust surface, and the rust removal is considered successful when the received surface acoustic wave signal is unchanged for 3 times.
Further, the voltage signal threshold is stored in the singlechip in the step S4, and the rust removal is considered successful by calculating the voltage signal difference between the front and the back times until the calculated voltage signal difference is smaller than the voltage signal threshold.
Example 2
In this embodiment, a laser rust removal state detection method includes the following steps:
s1: aiming at the determined required derusting threshold value and reflected light intensity threshold value of workpieces made of different materials, the energy temperature of laser during laser derusting is monitored in real time;
s2: by using the wavelength 1060nm, the pulse width 8ns, the energy 1.2J and the spot diameter 2.5mm
Carrying out single-point multiple laser irradiation on the rust degree, and sequentially collecting surface acoustic wave signals generated in the rust removal process by using a PVDF piezoelectric film;
s3: collecting light intensity information of the laser-induced plasma by adopting a photodiode, inputting the light intensity information into an oscilloscope, and converting the light intensity information of the laser-induced plasma into a voltage signal;
s4: the method comprises the steps of focusing by adopting a halogen tungsten lamp, projecting the focused halogen tungsten lamp on the surface of a derusting workpiece, reflecting the derusted workpiece to an optical fiber bundle by a focusing mirror, and collecting the derusted workpiece by using red, green and blue light detectors sequentially through a beam splitter;
s5: and transmitting real-time laser capability temperature, surface acoustic wave signals, piezoelectric signals and monitoring data of the red, green and basket photo detectors to the singlechip for analysis until all the four reach the standard, and completing rust removal.
Further, the determination formula of the rust removal threshold in S1 is: t is t v ≤t s ≤t m
Wherein: t is t v Is the vaporization temperature of the rust layer, t s Is the laser energy temperature, t m Is the melting point of the workpiece;
when t v ＝t s The rust removal threshold value of the workpiece is as t s ＝t m And is the damage threshold of the workpiece.
Further, t s The following equation is used to obtain:
wherein: f is laser energy density, R is workpiece surface reflectivity, K is thermal conductivity, a is thermal diffusivity, and t is laser pulse width.
Further, the effective area of the PVDF piezoelectric film in S2 is 1.2X3 cm, the thickness is 50 μm, and the PVDF piezoelectric film is adhered to the surface of the workpiece through double-sided adhesive.
Further, the surface acoustic wave signal in S4 changes with the continuous falling of the rust surface, and the rust removal is considered successful when the received surface acoustic wave signal is unchanged for 3 times.
Further, the voltage signal threshold is stored in the singlechip in the step S4, and the rust removal is considered successful by calculating the voltage signal difference between the front and the back times until the calculated voltage signal difference is smaller than the voltage signal threshold.
Test case
Test group: example 1, example 2, comparative document (patent application number 201010290349.5);
the testing method comprises the following steps: metals (10 metals of each metal are divided into two groups) with different materials (the same thickness and the corrosion conditions are not much different) are selected, laser rust removal is adopted, meanwhile, detection is respectively carried out by adopting the methods of examples and comparative files, and the rust removal result is tested:
it is obvious from the data that the invention adopts various methods to monitor simultaneously, is convenient for closing the laser power supply in time to stop rust removal, is green and environment-friendly, and can prevent metal matrix damage caused by excessive scanning while ensuring rust cleaning force, thereby effectively improving monitoring efficiency, reducing energy consumption and being more practical than comparative examples.
The present invention is not limited to the above-mentioned embodiments, and any person skilled in the art, based on the technical solution of the present invention and the inventive concept thereof, can be replaced or changed equally within the scope of the present invention.
Claims (2)
1. The laser rust removing state detecting method is characterized by comprising the following steps:
s1: aiming at the determined required derusting threshold value and reflected light intensity threshold value of workpieces made of different materials, the energy temperature of laser during laser derusting is monitored in real time; the determination formula of the rust removal threshold value is as follows: t is t v ≤t s ≤t m
In the above formula: t is t v Vapor as rust layerTemperature t of transformation s Is the laser energy temperature, t m Is the melting point of the workpiece;
when t v ＝t s The rust removal threshold value of the workpiece is as t s ＝t m The damage threshold value of the workpiece;
t s the following equation is used to obtain:
in the above formula: f is laser energy density, R is workpiece surface reflectivity, K is thermal conductivity, a is thermal diffusivity, t is laser pulse width;
s2: performing single-point multiple laser irradiation on the rust degree by using laser with the wavelength of 1060-1064nm, the pulse width of 8-10ns, the energy of 1-1.2J and the spot diameter of 2.5-3mm, and sequentially collecting surface acoustic wave signals generated in the rust removing process by using a PVDF piezoelectric film;
s3: collecting light intensity information of the laser-induced plasma by adopting a photodiode, inputting the light intensity information into an oscilloscope, and converting the light intensity information of the laser-induced plasma into a voltage signal; the surface of the photodiode is covered with a 1064nm attenuation sheet, a voltage signal threshold value is stored in the singlechip, and the voltage signal difference value between the front and the back is calculated until the calculated voltage signal difference value is smaller than the voltage signal threshold value, so that rust removal is considered to be successful;
s4: the method comprises the steps of focusing by adopting a halogen tungsten lamp, projecting the focused halogen tungsten lamp on the surface of a derusting workpiece, reflecting the derusted workpiece to an optical fiber bundle by a focusing mirror, and collecting the derusted workpiece by using red, green and blue light detectors sequentially through a beam splitter; the red, green and blue light detectors record reflected light intensity signals on the surface of the workpiece in real time, and the reflected light intensity of the red, green and blue light detectors is continuously changed along with rust cleaning until the reflected light intensity of the red, green and blue light detectors is equal to a reflected light intensity threshold value;
s5: transmitting real-time laser capability temperature, surface acoustic wave signals, piezoelectric signals and red, green and blue photo detector monitoring data to a singlechip for analysis until the laser capability temperature, the surface acoustic wave signals, the piezoelectric signals and the red, green and blue photo detector monitoring data reach the standard, and completing rust removal; the surface acoustic wave signal is changed along with the continuous falling of the rust surface, and the rust removal is successful when the received surface acoustic wave signal is unchanged for 3 times.
2. The method for detecting the rust removing state of the laser according to claim 1, wherein the effective area of the PVDF piezoelectric film in the S2 is 1.2x3 cm, the thickness is 50 μm, and the PVDF piezoelectric film is adhered to the surface of the workpiece through double-sided adhesive.
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| CN101655459B (en) * | 2009-09-18 | 2011-04-20 | 中国科学院安徽光学精密机械研究所 | Element spectral line reverse-extracting method of laser induced breakdown spectrum |
| CN102012373A (en) * | 2010-09-21 | 2011-04-13 | 江苏大学 | Laser derusting state monitoring method and device |
| CN103162941B (en) * | 2013-03-01 | 2016-11-16 | 长春理工大学 | A kind of optical thin film and photoelectric device surface laser device for measuring damage threshold |
| CN104748691B (en) * | 2015-03-05 | 2017-09-05 | 江苏大学 | The measurement apparatus and method of film thickness |
| CN109682795B (en) * | 2018-05-14 | 2023-09-22 | 西安工业大学 | Method for judging film damage based on plasma ignition time |
| CN109175710A (en) * | 2018-09-14 | 2019-01-11 | 东莞理工学院 | A kind of metal board laser derusting method |
| CN109813805B (en) * | 2019-01-28 | 2021-07-09 | 广东工业大学 | Laser cleaning process monitoring method based on acoustic emission technology |
| CN110618143B (en) * | 2019-10-25 | 2022-05-31 | 中国工程物理研究院上海激光等离子体研究所 | Method and system for testing laser damage threshold of wavelength separation film defect |
| CN113970540B (en) * | 2021-09-09 | 2023-07-04 | 华南师范大学 | Elemental isotope analysis system and method based on laser-induced plasma |
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