Low-power miniaturized self-stabilized laser rust removal device and method

Abstract

The application discloses a low-power small-sized automatic stable laser rust removal device, which comprises a laser light source module, laser emitted by the laser light source module enters the inside of a hand-held device module through an optical fiber, the inside of the hand-held device module is provided with a light path transmission assembly with adjustable displacement, laser is reflected after passing through the light path transmission assembly and is emitted from the hand-held device module, and the end of the hand-held device module from which the laser is emitted is provided with an ultraviolet sensor. The application further discloses a rust removal method of the rust removal device, and solves the problems of great labor intensity and low judgment accuracy caused by excessive dependence on manual operation in the prior rust removal mode.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of laser processing, and relates to a low-power miniaturized automatic stable laser rust removal device and a low-power miniaturized automatic stable laser rust removal method. BACKGROUND

[0002] The problems of over-ablation or under-ablation mainly come from the following aspects: (1) if the rust removal area has a surface with ups and downs, the distance between the laser light outlet and the rust removal surface changes all the time in the process of line-by-line scanning rust removal; (2) even if the rust removal area is an absolute plane, if the user's hand is difficult to keep stable, the distance between the laser light outlet and the rust removal surface will also change all the time in the process of line-by-line scanning rust removal; (3) the power density of the spot is too high and the moving speed of the spot is too slow, which leads to excessive ablation of the underlying metal layer.

[0003] The existing handheld online laser rust removal device has a certain divergence angle of the emitted light, and relies on the user's eyes to observe the color temperature of the gasification light and the ablation marks on the workpiece surface, and relies on the user's experience to judge whether the metal is over-ablated (referred to as "over-ablation") or the ablation thinning speed of the rust layer is too slow (referred to as "under-ablation"). Once over-ablation / under-ablation is found, the user needs to hold the device and move it backward / forward by a small distance, so that the spot area falling on the ablation surface increases / decreases, so that the unit area light power density decreases / increases, to ensure efficient removal of the oxide layer without damaging the underlying metal layer.

[0004] The above operation process requires high concentration of manual operation, and the accuracy of over-ablation / under-ablation judgment relying on user experience is also low. SUMMARY

[0005] The application aims to provide a low-power miniaturized automatic stable laser rust removal device, which solves the problems of high labor intensity and low judgment accuracy caused by excessive dependence on manual operation in the existing rust removal method.

[0006] Another object of the application is to provide a low-power miniaturized automatic stable laser rust removal method.

[0007] The first technical solution adopted by the application is a low-power miniaturized automatic stable laser rust removal device, which comprises a laser light source module. The laser emitted by the laser light source module enters the handheld module through an optical fiber. The handheld module is internally provided with a displacement-adjustable optical path transmission assembly. The laser is reflected by the optical path transmission assembly and then emitted from the handheld module. The end of the handheld module where the laser is emitted is provided with an ultraviolet sensor.

[0008] The first solution of the application is also characterized in that:

[0009] The handpiece module is an L-shaped hollow cylindrical structure, and the optical fiber enters the inside of the handpiece module from the bottom entrance of the handpiece module.

[0010] The light path transmission assembly comprises, in sequence along the laser incidence direction, a beam expander, a reflector and a convex lens, the beam expander is located in the vertical direction cylinder of the handpiece module, the reflector is located at the L-shaped corner of the handpiece module, and the convex lens is installed on the motorized slide table in the horizontal direction cylinder of the handpiece module.

[0011] The reflector is arranged at 45° with the horizontal direction, and the center of the convex lens and the center of the reflector are on the same horizontal line.

[0012] The number of ultraviolet sensors is three, and the three ultraviolet sensors are distributed at 120° between each other at the light outlet end of the handpiece module.

[0013] The three ultraviolet sensors are electrically connected with the photoelectric signal acquisition circuit, the output end of the photoelectric signal acquisition circuit is electrically connected with the input end of the hysteresis comparison circuit, the output end of the hysteresis comparison circuit is electrically connected with the input end of the motor driver, and the output end of the motor driver is electrically connected with the input end of the motorized slide table.

[0014] The second technical scheme adopted by the present application is a low-power miniaturized automatic stable laser rust removal method, which specifically comprises the following steps:

[0015] Step 1, turn on the laser light source module, the laser is incident to the beam expander through the optical fiber, and then sequentially passes through the reflector and the convex lens and is emitted from the handpiece module, at this time, the ultraviolet sensor starts to detect, the handpiece module is gradually moved close to the surface to be rusted, and in this process, the plasma radiation generated by ablation changes from nothing to something, so the ultraviolet radiation intensity V3 gradually starts to increase from zero, when 0<=V3<=alphaV th , the output voltage V out of the hysteresis comparison circuit is-V K , therefore the motorized slide table carrying the convex lens starts to move towards the initial end, causing the focal point to move towards the surface to be rusted, so that the light spot becomes smaller, the light spot power density becomes larger, V3 increases accordingly, until V3 first increases to betaV th .

[0016] Step 2, move the handpiece module to move the light spot in a line-by-line scanning manner, when V3 increases from betaV th to alphaV th , it means that over-ablation is about to occur, then the value of V out will change in a step change to +Vk, so that the motorized slide table carrying the convex lens starts to move towards the terminal end, causing the light spot to become larger, the light spot power density to become smaller, and V3 to become smaller accordingly.

[0017] Step 3, continue moving the handheld module to make the light spot move in a line-by-line scanning manner, when V3 moves from αV th Decrease to βV th This means that under-ablation is about to occur, then V out The value will step change to -V K This causes the electric slide to move towards the beginning of the convex lens, resulting in a smaller light spot and a larger light spot power density, which in turn causes V3 to increase.

[0018] Step 4: Repeat steps 2 and 3 until rust removal is complete.

[0019] The beneficial effects of this invention are that it shapes the laser into a focused beam and automatically adjusts the distance between the focal point and the surface to be derusted by monitoring the intensity of the ablation vaporization radiation. It also uses a hysteresis curve method with fast response and low cost to perform negative feedback control on the power density of the ablation spot, thereby achieving high-efficiency and low-damage laser rust removal. This solves the problem of over-ablation and under-ablation that easily occur in existing online handheld laser rust removal devices. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the low-power miniaturized automatic stabilized laser rust removal device of the present invention;

[0021] Figure 2 This is a schematic diagram of the installation position of the ultraviolet sensor in Embodiment 1 of the low-power miniaturized automatic stabilized laser rust removal device of the present invention;

[0022] Figure 3 This is a graph showing the relationship between the ultraviolet sensor signal intensity and the defocusing amount in Embodiment 1 of the low-power miniaturized automatic stabilized laser rust removal device of the present invention;

[0023] Figure 4 This is a schematic diagram of the hysteresis curve of the hysteresis comparison circuit in Embodiment 1 of the low-power miniaturized automatic stabilized laser rust removal device of the present invention;

[0024] Figure 5 This is a graph showing the relationship between the output signal of the hysteresis comparator circuit and the ultraviolet radiation intensity signal in Embodiment 3 of the low-power miniaturized automatic stabilized laser rust removal device of the present invention;

[0025] Figure 6 This is a schematic diagram of the hysteresis comparator circuit used in Embodiment 3 of the low-power miniaturized automatic stabilized laser rust removal device of the present invention;

[0026] Figure 7 This is a diagram showing the rust removal effect of Embodiment 3 of the low-power miniaturized automatic stabilized laser rust removal device of the present invention.

[0027] In the figure, 1. Electric slide, 3. Handheld module, 4. Reflector, 5. Laser source module, 7. Fiber optic, 8. Beam expander, 10. Convex lens, 11. Laser, 14. Ultraviolet sensor, 20. Photoelectric signal acquisition circuit, 21. Hysteresis comparator circuit, 22. Motor driver. Detailed Implementation

[0028] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0029] Example 1

[0030] The present invention provides a low-power, miniaturized, automatically stabilized laser rust removal device, the structure of which is as follows: Figure 1 As shown, it includes a handheld device module 3, a laser source module 5, and an optical fiber 7 connecting the two. The handheld device module 3 contains a convex lens 10, an electric slide 1, a reflector 4, and a beam expander 8. The handheld device module 3 has an L-shaped sleeve structure.

[0031] Fiber 7 originates from the laser source module 5, enters through the bottom light inlet of the handheld module 3, and connects to the beam expander 8 inside the handheld module 3. A reflector 4 is mounted at a 45° angle directly above the beam expander 8. An electric slide 1 is installed at the bottom inside the handheld module 3. The beginning of the electric slide 1 is located at the light outlet of the handheld module 3, and the end of the electric slide 1 is located at the L-shaped corner of the handheld module 3. A convex lens 10 is mounted on the electric slide 1, and the center of the convex lens 10 is at the same horizontal line as the center of the reflector 4.

[0032] The handheld module 3 has three identical ultraviolet sensors 14 installed at its light output port, with each sensor spaced 120° apart (e.g., ...). Figure 2 (As shown). All three ultraviolet sensors 14 are electrically connected to the photoelectric signal acquisition circuit 20. The output of the photoelectric signal acquisition circuit 20 is electrically connected to the input of the hysteresis comparator circuit 21. The output of the hysteresis comparator circuit 21 is electrically connected to the input of the motor driver 22. The output of the motor driver 22 is electrically connected to the input of the electric slide 23.

[0033] Laser 11 is transmitted from laser source module 5 along optical fiber 7 to beam expander 8, shaped into a uniform beam, reflected by reflector 4, and then emitted from handheld module 3 through convex lens 10.

[0034] According to linear optics, the maximum travel length L of the electric slide 1 is less than or equal to twice the focal length f of the convex lens 10, so as to avoid the convex lens 10 moving to the end of the electric slide 1 and the diameter of the emitted light beam at the light outlet of the handheld module 3 being greater than the inner diameter of the light outlet of the handheld module 3, causing light output blockage.

[0035] Because in actual operation, the laser beam emitted by the handheld module 3 cannot be aligned with the orientation of the surface to be derusted, in order to adapt to different surface orientations, based on the geometric principle that at least three points are needed to form a plane, three ultraviolet sensors 14 are used to form an ultraviolet receiving surface.

[0036] The photoelectric signal acquisition circuit 20 has three input ports and one output port. Its function is to add the three currents and linearly convert them into a voltage output, which is a conventional current-to-voltage conversion analog electronic circuit structure. The photocurrents of the three ultraviolet sensors 14 serve as the three input signals of the photoelectric signal acquisition circuit 20, which adds the photocurrents and linearly converts them into a voltage output signal (i.e., ultraviolet photoelectric response intensity V3).

[0037] Ablation and vaporization generate plasma. The main peak of the plasma radiation spectrum of most metals is in the ultraviolet (UV) band, while the main peak of the plasma radiation spectrum of oxygen is in the extreme ultraviolet (EUV) band and its peak value is lower than that of iron. Therefore, commonly available AlGaN, GaN, and SiC UV sensors 14 are sensitive to radiation from iron but insensitive to radiation from oxygen. Because rust layers contain abundant oxygen, the photoelectric response intensity output by the UV sensor 14 when the laser 11 ablates the rust layer is significantly lower than the photoelectric response intensity when the laser 11 ablates a rust-free metal surface. Using an AlGaN photodiode as the UV sensor 14, the results of measuring the ablation of an iron workpiece with a 1064nm wavelength laser are as follows. Figure 3 As shown, the amplitude of the V3 signal differs significantly between rusted and rust-free conditions. When the distance between the rust layer and the convex lens 10 is one time the focal length f of the convex lens 10 (i.e., the defocus is zero), the measured V3 signal value is called the over-ablation threshold. th express.

[0038] When V3 is greater than V th At this point, it means the rust layer has been burned away, and the metal beneath the rust layer begins to burn away, i.e., it is in an "over-burning" working state. Based on practical experience (such as...) Figure 3 As shown in the figure, when V3 is less than 0.2 times V th When the light spot power density is too low, the rust removal efficiency is low, meaning it is in a "under-ablation" working state. Therefore, to achieve high-efficiency and low-damage rust removal, V3 ∈ (0.2V) th V th ).

[0039] The input and output signals of the hysteresis comparator circuit 21 are V3 and V, respectively. out The function of the hysteresis comparator circuit 21 is:

[0040]

[0041] In the formula, α is a constant coefficient ranging from 0.7 to 0.9, and β is a constant coefficient ranging from 0.3 to 0.5. The hysteresis curve of the hysteresis comparator circuit 21 is shown below. Figure 4 As shown. The hysteresis curve represents the state of rise and fall of V3 (i.e., from V3 to V3). Positive and negative values ​​determine V out Characteristics of the transition value path. V out The upper limit of the hysteresis interval is αV th The lower limit is βV th Therefore, its center point potential V mid for:

[0042]

[0043] The reason for setting the upper limit of the hysteresis curve to be less than V is th And the lower limit is greater than 0.2V. th This is because in actual engineering, V is received from the motor driver 22. out When a signal changes, there is inevitably a certain delay in response time between the signal change and the actual change in the motor's direction of motion (e.g., deceleration before reversing). Therefore, an overshoot margin is required. (V) th -αV th ) and (βV th -0.2V th This refers to the overshoot margin reserved for the ablation feedback control system.

[0044] The function of motor driver 22 is to provide drive current to the motor inside the electric slide table 1 and to drive the motor according to the input signal V of motor driver 22. out Specify the forward / reverse direction of the internal motor of the electric slide 1, when V out When the voltage is positive, the motor rotates forward, causing the electric slide 1 to move towards the end. When V out When the voltage is negative, the motor reverses, causing the electric slide 1 to move toward the starting end.

[0045] Example 2

[0046] During implementation, possible reasons for V3 to increase are: 1) If the current V out The value is -V K 1) If the electric slide 1 moves towards the beginning, causing the light spot to shrink, V3 will increase; 2) If the distance between the current handheld module 3 and the rusted curved surface decreases, V3 will increase due to the shrinking light spot; 3) If a rust layer has been burned away but the handheld device is not moved to another adjacent area to be burned in time, V3 will increase rapidly due to the direct burning of rust-free metal (e.g., ...). Figure 3 (As shown).

[0047] During implementation, the possible reasons for V3 to decrease are: 1) If the current V out The value is +V K If the electric slide 1 moves toward the terminal, the light spot will become larger, causing V3 to decrease; 2) If the distance between the current handheld module 3 and the rusty curved surface increases, the light spot will become larger, causing V3 to decrease.

[0048] Based on Example 1, the rust removal method of the low-power miniaturized automatic stabilized laser rust removal device of the present invention specifically includes the following steps:

[0049] Step 1: Turn on the laser source module 5. The laser 11 is emitted from the handheld module 3, and the ultraviolet sensor 14 begins detection. Gradually bring the handheld module 3 closer to the surface to be derusted. During this process, the plasma radiation generated by ablation gradually increases from zero, thus the ultraviolet radiation intensity V3 gradually increases from zero. Figure 5 As shown, when 0≤V3≤αV th At that time, the output voltage V of the hysteresis comparator circuit 21 out The value is -Vk, so the electric slide 1 carrying the convex lens 10 begins to move towards the starting end, causing the focal point to move towards the surface to be derusted, making the light spot smaller and the power density of the light spot larger, and V3 increases accordingly, until V3 first rises to βV. th ;

[0050] Step 2, move the handheld module 3 to make the light spot move in a line-by-line scanning manner, when V3 moves from βV th Increase to αV th This means that ablation is about to occur, then V out The value will change to +Vk, causing the electric slide 1 carrying the convex lens 10 to start moving towards the end, resulting in a larger light spot and a smaller light spot power density, which in turn causes V3 to decrease.

[0051] Step 3, continue moving the handheld module 3 to make the light spot move in a line-by-line scanning manner, when V3 moves from αV th Decrease to βV th This means that under-ablation is about to occur, then V out The value will step change to -V K This causes the electric slide 1, carrying the convex lens 10, to begin moving towards the beginning, resulting in a smaller light spot and a larger light spot power density, which in turn causes V3 to increase.

[0052] Step 4: Repeat steps 2 and 3 until rust removal is complete.

[0053] In summary, the electric slide 1, by repeating in this way, can automatically compensate for the change in distance between the handheld module 3 and the rusted curved surface over time. It can also provide an automatic response measure to quickly reduce the light power density in response to the problem of ablation damage to the underlying metal. Therefore, it can keep the power density of the ablation spot always between "under-ablation" and "over-ablation", that is, achieve high-efficiency low-damage rust removal.

[0054] Example 3

[0055] The laser source module 5 uses an MFP-30W fiber laser with a wavelength of 1064nm, a pulse width of 100ns, an output power of 30W, and a repetition frequency of 60kHz. The convex lens 10 is a convex lens with a focal length of 15cm and an anti-reflection coating for the 1064nm wavelength. The reflector 4 is a K9 glass total reflection mirror with an anti-reflection coating for the 1064nm wavelength. The ultraviolet sensor 14 uses an LTK-G3535SGH photodiode. The beam expander 8 is a 5x beam expander quartz glass mirror. The metal plate to be rusted is a rusted iron plate. The motorized slide 1 is a GX28 slide with a travel of 10cm. The motor driver 22 uses an RZ7886 bidirectional motor driver IC. The photoelectric signal acquisition circuit 20 is a KDT860ID-AMP three-channel current adder.

[0056] Hysteresis comparator circuit 21 adopts the classic non-inverting hysteresis comparator circuit, and its circuit structure is as follows: Figure 6 As shown, the V3 signal is connected to resistor R1, which is connected to the non-inverting input of operational amplifier A. R1 is also connected to resistor R2, which is connected to the bidirectional Zener diode D. z (Its component's amplitude-stabilizing voltage value is ±V) K ), D z Grounded. Positive bias voltage source V cc Connect the slide wire rheostat R h One of the non-adjustable terminals, R h Another non-adjustable terminal is grounded, R h The adjustable terminal is connected to the inverting input of operational amplifier A. The output terminal of operational amplifier A is connected to a current-limiting resistor R, and R is connected to D. z The non-grounded terminal, D z The non-grounded terminal voltage is the output signal V of the hysteresis comparator circuit 21. out .

[0057] V mid The value is determined by R h The potential V at the adjustable terminal Rh R1 and R2 jointly determine:

[0058]

[0059] The width of the hysteresis interval (αV) th -βVth ) by V K R1 and R2 jointly determine:

[0060]

[0061] Measured over-ablation threshold V of rust th =2V, then the upper limit of the hysteresis interval of the hysteresis comparator circuit 21 is set to (αV) th = 1.6V, the lower limit of the hysteresis interval is (βV) th =0.8V, and operational amplifier A uses an LM358 op-amp.

[0062] With the light output port of handheld module 3 facing the surface to be derusted, and laser source module 5 turned on, laser 11 is emitted from handheld module 3. As handheld module 3 is gradually brought closer to the surface, the ultraviolet radiation intensity V3 gradually increases from zero. Figure 5 As shown, until V3 increases to αV th (meaning that over-ablation is imminent), then the electric slide 1 moves toward the end, causing V3 to drop until V3 drops to βV. th (meaning that under-ablation is imminent), then the electric slide 1 moves toward the starting end, causing V3 to rise. The electric slide 1, carrying the convex lens 10, moves back and forth continuously, thus maintaining the power density of the ablation spot between "under-ablation" and "over-ablation", thereby achieving high-efficiency, low-damage rust removal.

[0063] Implementation results are as follows Figure 7 As shown, when the distance between the light outlet of the handheld module 3 and the iron plate changes slightly (the change is less than 2.5cm), the rust layer can be completely removed and there is no significant thinning or loss of the iron metal under the rust layer.

Claims

1. A rust removal method using a low-power, miniaturized, automatically stabilized laser rust removal device, characterized in that: The low-power miniaturized automatic stabilized laser rust removal device includes a laser source module (5). The laser (11) emitted by the laser source module (5) enters the handheld module (3) through an optical fiber (7). The handheld module (3) is equipped with a displacement adjustable optical path transmission component. The laser (11) is reflected by the optical path transmission component and emitted from the handheld module (3). The end of the handheld module (3) from which the laser (11) is emitted is equipped with an ultraviolet sensor (14). The handheld device module (3) is an L-shaped hollow cylindrical structure, and the optical fiber (7) enters the handheld device module (3) from the bottom entrance of the handheld device module (3); The optical path transmission assembly includes a beam expander (8), a reflector (4) and a convex lens (10) arranged sequentially along the incident direction of the laser (11). The beam expander (8) is located in the vertical cylinder of the handheld module (3), the reflector (4) is located at the L-shaped corner of the handheld module (3), and the convex lens (10) is mounted on an electric slide (1) located in the horizontal cylinder of the handheld module (3). The reflector (4) is set at 45° to the horizontal direction, and the center of the convex lens (10) and the center of the reflector (4) are on the same horizontal line; The number of ultraviolet sensors (14) is three, and the three ultraviolet sensors (14) are distributed at 120° between each other at the light outlet end of the handheld module (3); All three ultraviolet sensors (14) are electrically connected to the photoelectric signal acquisition circuit (20). The output of the photoelectric signal acquisition circuit (20) is electrically connected to the input of the hysteresis comparison circuit (21). The output of the hysteresis comparison circuit (21) is electrically connected to the input of the motor driver (22). The output of the motor driver (22) is electrically connected to the input of the electric slide (1). Specifically, the steps include the following: Step 1: Turn on the laser source module (5). The laser (11) is incident on the beam expander (8) through the optical fiber (7), and then emitted from the handheld module (3) through the reflector (4) and the convex lens (10). At this time, the ultraviolet sensor (14) starts to detect. Gradually bring the handheld module (3) closer to the surface to be derusted. During this process, the plasma radiation generated by ablation increases from nothing to something. Therefore, the intensity of ultraviolet radiation increases. Starting from zero and gradually increasing, when At that time, the output voltage V of the hysteresis comparator circuit (21) out The value is -Vk, so the electric slide (1) carrying the convex lens (10) begins to move towards the beginning, causing the focal point to move towards the surface to be derusted, making the light spot smaller and the light spot power density larger. It then increased in size until V3 first rose to [a certain level]. ; Step 2, move the handheld module (3) to make the light spot move in a line-by-line scanning manner, when V3 moves from V th Rise to V th This means that ablation is about to occur, then V out The value will step change to +V K This causes the electric slide (1) carrying the convex lens (10) to begin moving towards the end, resulting in a larger light spot and a smaller light spot power density, leading to... It then becomes smaller; Step 3, continue moving the handheld module (3) to make the light spot move in a line-by-line scanning manner, when V3 moves from... V th Decrease to βV th This means that under-ablation is about to occur, then V out The value will step change to -V K This causes the electric slide (1) carrying the convex lens (10) to begin moving towards the starting end, resulting in a smaller light spot and a larger light spot power density, leading to... It will grow larger as a result; Step 4: Repeat steps 2 and 3 until rust removal is complete.

Images