CN111957676B - Laser cleaning online monitoring device and method based on temperature sensing - Google Patents
Laser cleaning online monitoring device and method based on temperature sensing Download PDFInfo
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- CN111957676B CN111957676B CN202010819622.2A CN202010819622A CN111957676B CN 111957676 B CN111957676 B CN 111957676B CN 202010819622 A CN202010819622 A CN 202010819622A CN 111957676 B CN111957676 B CN 111957676B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B08—CLEANING
- B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
- B08B7/00—Cleaning by methods not provided for in a single other subclass or a single group in this subclass
- B08B7/0035—Cleaning by methods not provided for in a single other subclass or a single group in this subclass by radiant energy, e.g. UV, laser, light beam or the like
- B08B7/0042—Cleaning by methods not provided for in a single other subclass or a single group in this subclass by radiant energy, e.g. UV, laser, light beam or the like by laser
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- B—PERFORMING OPERATIONS; TRANSPORTING
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- B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
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Abstract
The invention relates to a laser cleaning online monitoring device and method based on temperature sensing, wherein the device comprises a laser cleaning device and an online monitoring device; judging whether the object to be cleaned is suitable for the monitoring method or not according to the parameters of the laser; placing the surface of an object to be cleaned in the range of the focused laser beam waist, and starting a laser cleaning device and an online monitoring device to perform laser cleaning; carrying out laser cleaning for many times until a voltage change curve tends to be stable and unchanged, and stopping laser cleaning; observing whether the surface of the object to be cleaned has burning marks, and if so, carrying out laser cleaning again; if the burn mark does not exist, the laser cleaning is finished. The laser cleaning online monitoring device and the laser cleaning online monitoring method can accurately judge whether the object to be cleaned is cleaned or not by utilizing different thermal physical parameters of different substances, and solve the problem that the surface of the object to be cleaned cannot be accurately judged to be cleaned or not through manual visual observation.
Description
Technical Field
The invention relates to the field of laser cleaning and online monitoring, in particular to a laser cleaning online monitoring device and method based on temperature sensing.
Background
The conventional cleaning method used in the industry is to use two methods of chemical agent and mechanical cleaning. But the cleaning with chemical agents has great probability of causing environmental pollution and is not in accordance with the environmental protection policy of China; and the mechanical cleaning is difficult to control the precision and is easy to damage the substrate. The laser cleaning has the following advantages: (1) the laser cleaning method does not need any chemical agent, and is a green cleaning method. (2) The laser cleaning is non-contact cleaning, and no secondary pollution exists. (3) The laser cleaning can realize remote operation and ensure the safety of workers. (4) The application range of laser cleaning can remove various pollutants on the surfaces of various materials, and the cleanness which cannot be achieved by conventional cleaning is achieved. (5) The laser cleaning efficiency is high, and the time is saved.
At present, whether the laser cleaning surface is cleaned or not is judged mainly by means of manual visual observation, whether the cleaned surface is cleaned or not is difficult to judge accurately, and meanwhile, in order to avoid damage to a substrate due to excessive laser cleaning times or uncleaned due to too few cleaning times, it is necessary to research a laser cleaning online monitoring device and method; the laser cleaning online monitoring device can effectively improve the efficiency of laser cleaning and ensure that objects to be removed on the surface can be completely removed in the shortest time. The current commonly used laser cleaning monitoring method is mainly a laser-induced breakdown spectroscopy technology, but the method has the defects of high manufacturing cost and high requirement on the technical level of operators at present.
Disclosure of Invention
The purpose of the invention is as follows:
the invention provides a temperature sensing-based laser cleaning online monitoring device and method, and aims to solve the problems that whether the surface of an object to be cleaned is cleaned or not can not be accurately judged by manual visual observation, and the technical level of an operator is high due to the high manufacturing cost of a laser-induced breakdown spectroscopy technology.
The technical scheme is as follows:
a laser cleaning online monitoring device based on temperature sensing comprises a laser cleaning device and an online monitoring device;
the laser cleaning device comprises a laser, a light guide system, a laser head, an electric push rod, a Z-axis moving cantilever and an XY-axis moving platform, wherein one end of the Z-axis moving cantilever is connected with the laser, the other end of the Z-axis moving cantilever is fixedly connected with the laser head, the light guide system is arranged inside the corner of the Z-axis moving cantilever, the lower end of the Z-axis moving cantilever is connected with the electric push rod, the XY-axis moving platform is arranged below the laser head, and an object to be cleaned is placed on the XY-axis moving platform;
the online monitoring device consists of a temperature sensor, a voltage signal amplifier, an oscilloscope high-voltage probe, an oscilloscope and an upper computer, wherein the signal output end of the temperature sensor is connected with the signal input end of the voltage signal amplifier, the signal output end of the signal amplifier is connected with the input interface of the oscilloscope by the oscilloscope high-voltage probe, the input interface of the oscilloscope is in wired connection with the upper computer, and the temperature sensor is arranged at the end part of the electric push rod.
The distance between the electric push rod and the laser head is to ensure that the information acquisition point of the temperature sensor and the laser cleaning point are always kept at a distance of 9-11 cm.
The wavelength of the laser is 1064nm, the working power is 0-1500W, the pulse width is 90-150ns, and the repetition frequency is 10-60 KHz.
The temperature sensor is a non-contact infrared temperature sensor, and the temperature measurement range is 0-1100 ℃.
The signal gain multiple range of the voltage signal amplifier is 1-1500 times, and the multiple is adjustable.
A laser cleaning online monitoring method based on temperature sensing comprises the following steps:
step 1) judging whether an object to be cleaned is suitable for the monitoring method or not according to the parameters of the laser;
step 2) placing the surface of the object to be cleaned in the range of the focused laser beam waist, and starting a laser cleaning device and an online monitoring device to perform laser cleaning;
step 3) carrying out laser cleaning for multiple times, and recording a voltage change curve of the object to be cleaned by laser cleaning each time through an upper computer; stopping laser cleaning until the voltage change curve tends to be stable and unchanged;
step 4) observing whether the surface of the object to be cleaned has burning marks, if so, reducing the power of the laser, returning the cleaning frequency to zero, and then carrying out the laser cleaning in the step 3); if the burning mark does not exist, the surface of the object to be cleaned is cleaned, and the laser cleaning is finished.
In the step 1), whether the object to be cleaned is suitable for the monitoring method is judged by the following formula:
wherein: lambda-absorption of laser light by the material; P/(W) -laser power; r/(cm) -laser spot radius; K/(W/cm. DEG C) -thermal conductivity of the material; sabV/° c) is the seebeck coefficient of the thermoelectric material in the non-contact temperature sensor; t is0/(. degree.C.) is room temperature.
The frequency range of the multiple laser cleaning in the step 3) is more than or equal to 5 times, and the parameters, the cleaning direction and the cleaning initial position of the laser for the multiple laser cleaning are the same as those set in the 1 st laser cleaning.
If the voltage change curve of the last time in the step 3) is not stable, the power of the laser needs to be increased, the cleaning frequency is reduced to zero, and the laser cleaning in the step 3) is carried out again.
The standard for judging whether the voltage change curve tends to be stable in the step 3) is the voltage peak of the last voltage change curve and the previous voltage change curve.
The advantages and effects are as follows:
(1) the laser cleaning online monitoring device and the laser cleaning online monitoring method can accurately judge whether the object to be cleaned is cleaned or not by utilizing different thermal physical parameters of different substances, and solve the problem that the surface of the object to be cleaned cannot be accurately judged to be cleaned or not through manual visual observation.
(2) The laser cleaning online monitoring device has the advantages of simple structure, convenient operation, low manufacturing cost and low requirement on the technical level of operators, and can be applied to other laser cleaning occasions;
(3) the monitoring method adopted by the invention has strong anti-interference capability, can ensure that the polluted surface can be cleaned, and has higher cleaning efficiency.
Drawings
FIG. 1 is a schematic diagram of a laser cleaning online monitoring device based on temperature sensing, which is constructed by the invention;
FIG. 2 is a schematic diagram of signal transmission during on-line monitoring according to the present invention;
FIG. 3 is a flow chart of the operation of the laser cleaning on-line monitoring method of the present invention;
FIG. 4 is a comparison of the cleaning effect of the device before the surface of the rusted iron plate is cleaned by laser;
reference numerals:
1. the device comprises a laser, 2, a light guide system, 3, a laser head, 4, a temperature sensor, 5, a voltage signal amplifier, 6, an oscilloscope high-voltage probe, 7, an oscilloscope, 8, an upper computer, 9, an object to be cleaned, 10, an XY axis moving platform, 11, a USB data line, 12, an electric push rod, 13 and a Z axis moving cantilever.
Detailed Description
In order to make the structure, technical principles and implementation methods of the present invention more intuitive and clear, the following examples and drawings are given.
The monitoring principle involved in the invention is that the pollutants and the matrix both absorb heat and rise temperature under the irradiation of laser; however, since different materials have different thermal physical parameters, the temperature rise rate and the temperature peak value of the two materials are different when the materials are cleaned, and the measured voltage peak value is also different. Under the condition that the parameters of the laser, the cleaning direction and the cleaning starting position of each cleaning are kept the same, according to the monitoring principle, after the surface to be cleaned is cleaned for many times, if the drawn voltage peak value change curve is increased along with the cleaning times, the voltage peak value change curve is reduced from a high point and finally tends to be stable and unchanged, namely when the voltage peak value is not changed along with the laser cleaning times, the cleaned surface is indicated to be cleaned.
The invention is suitable for the condition that the thermophysical properties of the substrate and the pollutants on the surface of the substrate are different, such as removing metal oxides, rubber particles, paint and the like on the surface of the substrate by laser.
As shown in fig. 1, a laser cleaning online monitoring device based on temperature sensing comprises a laser cleaning device and an online monitoring device;
as shown in fig. 1, the laser cleaning device comprises a laser 1, a light guide system 2, a laser head 3, an electric push rod 12, a Z-axis moving cantilever 13 and an XY-axis moving platform 10, wherein the light guide system 2 is composed of a reflector and a focusing lens; a focusing lens is arranged in the laser head 3; laser head 3 is installed on Z axle removes cantilever 13, and the one end that Z axle removed cantilever 13 is connected with laser instrument 1, and the other end and the laser head 3 fixed connection of Z axle removal cantilever 13, the inside of Z axle removal cantilever 13 corner is provided with leaded light system 2, and the lower extreme that Z axle removed cantilever 13 is connected with electric putter 12 to realize that information acquisition point and laser cleaning point move simultaneously. An XY-axis moving platform 10 is arranged below the laser head 3, and an object to be cleaned 9 is placed on the XY-axis moving platform 10; the XY axis moving stage 10 is independent with respect to the bar 12 and the cantilever 13. The electric push rod 12 is fixedly connected with the Z-axis movable cantilever 13 through clamping or welding and the like.
The electric push rod 12 is a connecting structure which can realize horizontal feeding movement in the axial direction, and the electric push rod 12 is an electric push rod 12 with a built-in potentiometer, so that stroke control can be realized. The electric push rod 12 mainly comprises a motor, a gear set, a screw, a nut and an inner tube with an outer sleeve, wherein the outer sleeve is fixed on the Z-axis moving cantilever 13, the motor is arranged in the outer sleeve and is connected with the gear set, the gear set is connected with the screw nut, the nut is fixedly connected with the inner tube, and the outer sleeve is connected with the inner tube through a limiting slide way; when the motor rotates, the gear set drives the screw rod to rotate, and the nut on the screw rod drives the inner pipe to perform horizontal feeding motion in the axial direction of the outer sleeve, so that the horizontal displacement of the temperature sensor 4 is realized.
The Z-axis moving cantilever 13 is a connecting structure which can realize the feeding motion in the Z-axis direction, the Z-axis moving cantilever 13 is fixed on a sliding block, the sliding block is arranged on a guide rail and is matched with a lead screw, and when a motor drives the lead screw to rotate, the lead screw can enable the sliding block to move along the guide rail direction; the guide rail is vertically (Z-axis direction) installed and fixed on an outer frame constructed by aluminum profiles, the sliding block drives the movable cantilever 13 to move in the Z-axis direction, and the laser head 3 is fixed on the Z-axis movable cantilever 13, so that the feeding motion of the laser head 3 in the Z-axis direction is realized.
The XY axle moving platform 10 is a structure which can move along the X axle and the Y axle, the XY axle moving platform 10 in the invention includes the guide rail in the X axle direction, the guide rail in the Y axle direction and the objective table, the guide rail in the X axle direction and the guide rail in the Y axle direction have the same structure, and both comprise a lead screw, a slide rail and a motor, the guide rail in the X axle direction is installed on the guide rail in the Y axle direction through a first slide block, the first slide block is connected with the lead screw in the Y axle direction in a threaded manner and is matched, namely, the motor of the guide rail in the Y axle direction drives the lead screw to rotate, and the guide rail in the X axle direction can be driven to move along the guide rail in the Y axle direction through the first slide block; and when the motor of the X-axis direction guide rail controls the rotation of the lead screw in the X-axis direction, the second slide block moves along the guide rail in the X-axis direction. The second slide block is provided with an object stage for placing the object 9 to be cleaned. The XY-axis moving platform 10 is installed and fixed on an outer frame constructed of aluminum profiles. The connection can realize the movement of the object stage for placing the object 9 to be cleaned in the X-axis and Y-axis directions.
The Z-axis moving arm 13 on which the laser head 3 is mounted is movable in the Z-axis direction, and the XY-axis moving table 10 on which the object 9 to be cleaned is placed is movable in the X-axis and Y-axis directions.
As shown in fig. 2, the online monitoring device is composed of a temperature sensor 4, a voltage signal amplifier 5, an oscilloscope high-voltage probe 6, an oscilloscope 7 and an upper computer 8, wherein the temperature sensor 4, the voltage signal amplifier 5, the oscilloscope high-voltage probe 6, the digital oscilloscope 7 and the upper computer 8 are sequentially connected in a line, the digital oscilloscope 7 and the upper computer 8 are connected through a USB data line 11, specifically, a signal output end of the temperature sensor 4 is connected with a signal input end of the voltage signal amplifier 5, a signal output end of the signal amplifier 5 is connected with an input interface of the oscilloscope 7 through the oscilloscope high-voltage probe 6, an input interface of the oscilloscope 7 is in a wired connection with the upper computer 8 through the USB data line 11, and oscilloscope control software and data fitting software are installed in the upper computer 8. The temperature sensor 4 is mounted on the end of the electric putter 12. Temperature information of the cleaning process can be monitored in real time; and the electric push rod 12 is used for adjusting and fixing the distance between the information acquisition point and the laser cleaning point.
The non-contact infrared temperature sensor 4 in the on-line monitoring device transmits the acquired data to the oscilloscope 7 through the oscilloscope high-voltage probe 6, the signal is amplified by the voltage signal amplifier 5, and the oscilloscope 7 transmits the signal to the upper computer 8. The curve is synchronously displayed on an upper computer 8 through oscilloscope 7 control software. And finally, controlling a measurement function in software by using an oscilloscope 7 to obtain a voltage peak value corresponding to each cleaning process, and drawing a curve graph of the peak value change of each time by using data fitting software.
The oscilloscope 7 is a digital oscilloscope 7. The digital oscilloscope 7 is a digital oscilloscope with a USB Device interface; the USB Device interface of the oscilloscope is connected with the USB port of the upper computer by a USB data wire. Oscilloscope control software installed in the upper computer is used for acquiring curves in the oscilloscope in real time, and can remotely control the oscilloscope, so that an operator can observe the change of the curves and measure the relevant data of the curves conveniently.
The distance between the electric push rod 12 and the laser head 3 is to ensure that the information acquisition point of the temperature sensor 4 and the laser cleaning point are always kept at a distance of 9-11cm and move simultaneously, so that the accuracy of temperature information can be ensured. So as to improve the monitoring precision and sense the temperature change in real time. When the distance is less than 9cm, the temperature sensor 4 is easily damaged during laser cleaning, so that the data monitored by the temperature sensor 4 has large fluctuation and inaccurate data; when the distance is larger than 11cm, the monitoring distance is far, and the data is inaccurate. The application preferably always maintains a distance of 10 cm.
The laser adopts Nd: YAG laser. The wavelength of the laser 1 is 1064nm, the working power is 0-1500W, the pulse width is 90-150ns, and the repetition frequency is 10-60 KHz. The cleaning machine can meet the requirements that cleaning is finished by selecting proper power, pulse width and repetition frequency for different objects to be cleaned in different cleaning occasions, and the best cleaning effect is achieved.
The temperature sensor 4 is a non-contact infrared temperature sensor, and the temperature measurement range is 0-1100 ℃. When laser cleaning occurs, the surface temperature of the object to be cleaned 9 reaches thousands of degrees; since the elements of a general contact temperature sensor cannot withstand such a high temperature, a non-contact infrared temperature sensor is used. The upper measurement limit of the non-contact infrared temperature sensor is not limited by the heat resistance of the temperature sensing element, and the maximum temperature that can be measured in principle is not limited. And the non-contact temperature sensor is suitable for sensing the condition of rapid temperature change. Although the metal matrix has a slight influence on the temperature measurement accuracy of the infrared temperature sensor, the monitoring principle and the monitoring result of the invention are not influenced.
The signal gain multiple range of the voltage signal amplifier 5 is 1-1500 times, and the multiple is adjustable; the waveform obtained in the oscilloscope 7 can be more accurate by conveniently selecting a proper multiple.
As shown in fig. 3, a laser cleaning online monitoring method based on temperature sensing includes the following steps:
step 1) judging whether the object 9 to be cleaned is suitable for the monitoring method according to the parameters of the laser 1;
whether the object 9 to be cleaned is suitable for the monitoring method is judged by the following formula:
wherein λ -the absorption of laser light by the material; P/(W) -laser power; r/(cm) -laser spot radius; K/(W/cm. DEG C) -thermal conductivity of the material; sabV/° c) is the seebeck coefficient of the thermoelectric material in the non-contact temperature sensor; t is0/(. degree.C.) is room temperature.
At the laser power P, the laser spot radius r and the Seebeck coefficient SabAnd room temperature T0Under the condition of numerical value determination, the absorptivity lambda and the thermal conductivity K of the object to be removed on the surface of the matrix and the matrix are respectively substituted into a formula, and if the calculated voltage values corresponding to the object to be removed on the surface and the matrix are obviously different, the object to be cleaned 9 is suitable for the monitoring method.
Step 2) placing the surface of the object to be cleaned 9 in the range of the focused laser beam waist, and starting a laser cleaning device and an online monitoring device to perform laser cleaning;
after the object 9 to be cleaned is judged to be suitable for the monitoring method through the step 1), the surface of the object 9 to be cleaned is placed in the range of the focused laser beam waist by adjusting the electric push rod 12, the Z-axis moving cantilever 13 and the XY-axis moving platform 10, and the laser cleaning device and the online monitoring device are started for laser cleaning.
After the laser is output from the laser 1, the laser is conducted to the laser head 3 through the light guide system 2, and finally, the laser is focused by the focusing lens in the laser head 3 and then is output from the laser head 3. And placing the object 9 to be cleaned on the XY-axis moving platform 10, and then controlling the XY-axis moving platform 10 to place the object 9 to be cleaned below the laser head 3. The laser head 3 moves in the Z-axis direction by adjusting the cantilever 13, so that the surface of the object 9 to be cleaned is positioned in the range of the focused laser beam waist. The electric push rod 12 is adjusted to fix the distance between the information acquisition point of the non-contact infrared temperature sensor 4 and the laser cleaning point at 10 cm.
The parameters of the laser 1 are set as follows: the power is 180W, the repetition frequency is 10KHz, the scanning speed is 1500mm/s, and the pulse width is 140 ns. After setting the parameters of the laser 1, turning on the laser 1; after the laser is output from the laser 1, the laser is conducted to the laser head 3 through the light guide system 2, and finally the laser is output from the laser head 3 after being focused by the focusing lens in the laser head 3, and a light spot is formed on the surface to be cleaned.
Step 3) carrying out laser cleaning for multiple times, and recording a voltage change curve of the object to be cleaned 9 by the upper computer 8 for each laser cleaning; and stopping laser cleaning until the voltage change curve tends to be stable and unchanged.
And the upper computer 8 records the voltage change curve of the object to be cleaned 9 in the 1 st laser cleaning, and then carries out the 2 nd laser cleaning to the 5 th laser cleaning in sequence.
In the laser cleaning process, the temperature sensor 4 outputs a voltage signal and transmits the voltage signal to the voltage signal amplifier 5, and the signal gain multiple of the voltage signal amplifier 5 is set to be 500 times; the voltage signal is amplified and then transmitted to an oscilloscope 7 from the signal amplifier 5; the oscilloscope 7 transmits the voltage change curve into the upper computer 8, and displays the voltage change curve on the upper computer 8 in real time through oscilloscope control software.
The method specifically comprises the following steps: the laser 1 is turned on to start cleaning the surface of the object 9 to be cleaned for the first time. The laser output by the laser head 3 directly irradiates the surface of the object 9 to be cleaned, and the surface temperature of the cleaning point is rapidly increased. At the same time, the XY-axis moving stage 10 starts moving at a uniform speed in one direction, and a "snap" sound is heard during this process, which indicates that the contaminants on the surface of the object 9 to be cleaned are being removed. The oscilloscope control software can display the voltage change curve displayed by the oscilloscope 7 in the cleaning process on the upper computer 8 in real time, and can remotely adjust the display mode of the curve in the oscilloscope 7 through the oscilloscope control software. After the first cleaning is finished, the voltage peak value of the voltage change curve is measured by using oscilloscope control software and recorded in data fitting software.
In order to ensure the accuracy of monitoring by making the measured multiple voltage peaks represent the same cleaning region, the parameters, cleaning direction and cleaning starting position of the laser 1 of the multiple laser cleaning are the same as those of the 1 st laser cleaning.
Specifically, the parameters of the laser 1, the laser cleaning start position and the laser cleaning direction are all kept unchanged, then the second cleaning is started, and after the second cleaning is completed, the voltage peak value of the voltage change curve is recorded in data fitting software. Similarly, the parameters of the laser 1, the laser cleaning start position and the direction are all kept unchanged, and the cleaning is performed for the third time in sequence. After 5 total washes in this manner, the voltage peaks for the 5 laser washes were recorded and plotted in the data fitting software for the 5 washes.
Judging whether the surface cleaning times of the object to be cleaned 9 are more than or equal to 5 times; if the number of times is less than 5, the laser cleaning is continued, and if the number of times is more than or equal to 5, whether the last voltage change curve drawn in the upper computer 8 tends to be stable and unchanged or not needs to be observed.
Whether the cleaning is finished or not is judged by observing whether a voltage peak value change curve drawn in the upper computer 8 is stable or not. Because there is the influence of all kinds of factors can lead to monitoring to have certain error when wasing, whether the voltage peak value change curve tends to steadily unchangeable for following rule judgement: whether the difference between the voltage peak value of the last cleaning and the voltage peak value of the previous cleaning is within +/-0.1V or not; if within + -0.1V, it is considered to be stationary, and if beyond + -0.1V, it is considered to be not stationary. The unstable situation of the voltage change curve is that after five times of cleaning, the voltage peak value in the voltage peak value change curve does not always have the situation that the voltage peak value change curve decreases from a high point and finally tends to be stable along with the increase of the cleaning times, and the situation indicates that surface cleaning does not occur or is not cleaned, and the laser power needs to be increased; or, although already smooth, the cleaned substrate surface becomes dark yellow with slight burn marks, indicating excessive ablation and requiring a reduction in laser power.
With the increase of the cleaning times, the voltage peak value change curve is reduced from a high point and finally tends to be stable and unchanged, namely when the voltage peak value does not change along with the laser cleaning times, the surface is indicated to be cleaned, and the next operation can be carried out.
The temperature sensor 4 outputs a voltage signal after sensing the temperature change of the surface of the object 9 to be cleaned; the voltage signal is amplified by a voltage signal amplifier 5 and then transmitted to an oscilloscope 7, and a voltage change curve is displayed on a screen of the oscilloscope 7; and the USB Device port of the oscilloscope 7 is connected with the USB port of the upper computer 8 by a USB data wire 11, so that the voltage change curve displayed in the oscilloscope 7 is transmitted to the upper computer 8.
The oscilloscope control software can display the voltage change curve in the oscilloscope 7 on the upper computer 8 in real time, and can remotely control the oscilloscope 7 to complete the measurement of various data of the voltage change curve.
Measuring the voltage peak value of each cleaning process by using a measuring function in oscilloscope control software, and recording the voltage peak value of each time into data fitting software; and then drawing a voltage peak value change curve after 5 times of cleaning by using data fitting software.
And 4) if the voltage change curve in the step 3) is stable and unchanged, observing whether the surface of the object to be cleaned (9) has burning marks, wherein the burning marks are that the surface of the object to be cleaned loses metal luster and becomes dark. If the burn mark exists, reducing the power of the laser (1), returning the cleaning frequency to zero, and carrying out the laser cleaning in the step 3) again; if the burn mark does not exist, the surface of the object to be cleaned (9) is cleaned, and the laser cleaning is finished.
During laser cleaning, the roughness and the laser absorption coefficient of the pollutants are larger than those of the object to be cleaned 9 which takes iron as a main material, so that the temperature peak values of the pollutants and the die are greatly different, and the voltage peak values measured by the pollutants and the die are also greatly different; so that whether the surface of the object 9 to be cleaned is cleaned can be judged according to the voltage peak value change curve. If the voltage peak value change curve drawn by the data fitting software decreases from a high point and finally tends to be stable along with the increase of the cleaning times, namely the situation that the voltage peak value does not change along with the laser cleaning times occurs, the situation shows that the laser starts to act on the surface of the substrate and the surface of the object to be cleaned 9 is cleaned; meanwhile, the cleaned surface of the object 9 to be cleaned is changed from carbon black to silver white and has metallic luster.
The laser cleaning online monitoring device and method based on temperature sensing are simple in monitoring method, monitoring results are easy to judge and reliable, and cleaning of surface attachments of other materials and monitoring of a cleaning process can be achieved only by changing parameters of the laser 1.
The cleaning result of the device and the method for cleaning the rusted iron plate surface is shown in fig. 4, wherein (a) in fig. 4 is an effect diagram before cleaning, (b) is an effect diagram of primary cleaning, (c) is an effect diagram of secondary cleaning, and (d) is an effect diagram of the last cleaning. Fig. 4 shows the effect of the rusted iron plate before and after cleaning, wherein a large amount of rusted matter covers the surface of the rusted iron plate before and after cleaning; when the device is adopted to carry out laser cleaning to the last cleaning, namely the difference between the voltage peak value of the last cleaning and the voltage peak value of the previous cleaning is within +/-0.1V; that is, fig. 4(d) shows that the rusted iron plate surface cleaned by the method has substantially no rusted material, and the color of the metal itself is completely exposed, i.e. cleaned.
Claims (10)
1. The utility model provides a laser washs online monitoring devices based on temperature perception which characterized in that:
the device comprises a laser cleaning device and an online monitoring device;
the laser cleaning device comprises a laser (1), a light guide system (2), a laser head (3), an electric push rod (12), a Z-axis moving cantilever (13) and an XY-axis moving platform (10), one end of the Z-axis moving cantilever (13) is connected with the laser (1), the other end of the Z-axis moving cantilever (13) is fixedly connected with the laser head (3), the light guide system (2) is arranged inside a corner of the Z-axis moving cantilever (13), the electric push rod (12) is connected to the lower end of the Z-axis moving cantilever (13), the XY-axis moving platform (10) is arranged below the laser head (3), and an object to be cleaned (9) is placed on the XY-axis moving platform (10);
the online monitoring device is composed of a temperature sensor (4), a voltage signal amplifier (5), an oscilloscope high-voltage probe (6), an oscilloscope (7) and an upper computer (8), wherein the signal output end of the temperature sensor (4) is connected with the signal input end of the voltage signal amplifier (5), the signal output end of the voltage signal amplifier (5) is connected with the input interface of the oscilloscope (7) through the oscilloscope high-voltage probe (6), the input interface of the oscilloscope (7) is in wired connection with the upper computer (8), and the temperature sensor (4) is installed at the end part of an electric push rod (12).
2. The laser cleaning online monitoring device based on temperature sensing of claim 1, wherein: the distance between the electric push rod (12) and the laser head (3) is to ensure that the information acquisition point of the temperature sensor (4) is always kept at a distance of 9-11cm from the laser cleaning point.
3. The laser cleaning online monitoring device based on temperature sensing of claim 1, wherein: the wavelength of the laser (1) is 1064nm, the working power is 0-1500W, the pulse width is 90-150ns, and the repetition frequency is 10-60 KHz.
4. The laser cleaning online monitoring device based on temperature sensing of claim 1, wherein: the temperature sensor (4) is a non-contact infrared temperature sensor, and the temperature measurement range is 0-1100 ℃.
5. The laser cleaning online monitoring device based on temperature sensing of claim 1, wherein: the signal gain multiple range of the voltage signal amplifier (5) is 1-1500 times, and the multiple is adjustable.
6. The temperature-sensing-based laser cleaning online monitoring method of the temperature-sensing-based laser cleaning online monitoring device according to claim 1, wherein the temperature-sensing-based laser cleaning online monitoring method comprises the following steps:
the method comprises the following steps:
step 1) judging whether the object (9) to be cleaned is suitable for the monitoring method according to the parameters of the laser (1);
step 2) placing the surface of the object to be cleaned (9) in the range of the focused laser beam waist, and starting a laser cleaning device and an online monitoring device to perform laser cleaning;
step 3) carrying out laser cleaning for multiple times, and recording a voltage change curve of the object to be cleaned (9) to be cleaned by laser cleaning each time through an upper computer (8); stopping laser cleaning until the voltage change curve tends to be stable and unchanged;
step 4) observing whether the surface of the object to be cleaned (9) has burning marks, if so, reducing the power of the laser (1), returning the cleaning frequency to zero, and then carrying out the laser cleaning in the step 3) again; if the burn mark does not exist, the surface of the object to be cleaned (9) is cleaned, and the laser cleaning is finished.
7. The laser cleaning online monitoring method based on temperature sensing as claimed in claim 6, wherein: in the step 1), whether the object (9) to be cleaned is suitable for the monitoring method is judged by the following formula:
wherein: lambda-absorption of laser light by the material; P/(W) -laser power; r/(cm) -laser spot radius; K/(W/cm. DEG C) -thermal conductivity of the material; sabV/° c) is the seebeck coefficient of the thermoelectric material in the non-contact temperature sensor; t is0/(. degree.C.) is room temperature.
8. The laser cleaning online monitoring method based on temperature sensing as claimed in claim 6, wherein:
the frequency range of the multiple laser cleaning in the step 3) is more than or equal to 5 times, and the parameters, the cleaning direction and the cleaning initial position of the laser (1) of the multiple laser cleaning are the same as those of the 1 st laser cleaning.
9. The laser cleaning online monitoring method based on temperature sensing as claimed in claim 6, wherein:
if the voltage change curve of the last time in the step 3) is not stable, the power of the laser (1) needs to be increased, the cleaning frequency is reduced to zero, and the laser cleaning in the step 3) is carried out again.
10. The laser cleaning online monitoring method based on temperature sensing as claimed in claim 6, wherein:
the standard for judging whether the voltage change curve tends to be stable in the step 3) is whether the difference between the voltage peak values of the last voltage change curve and the previous voltage change curve is within the range of +/-0.1V.
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