A water jet quality detection device and detection method using water-guided laser

Abstract

The invention belongs to the technical field of water-guided lasers, and relates to a water jet quality detection device and a detection method for water-guided lasers, comprising: a coupling system, a laser water jet, a first detector, and a second detector. The coupling system couples a laser beam in a high-pressure water jet to form a laser water jet. The first detector and the second detector are both annular, and a plurality of photosensitive sheets are evenly distributed around the annular inner rings of the first detector and the second detector. The invention adopts a method of arranging a plurality of detectors at different heights in the direction of the laser water jet, arranging a plurality of evenly distributed photosensitive sheets in the detector with the detection surface radially facing the direction of the laser water jet, detecting the real-time state of total reflection at different heights and angles, and realizing quantitative evaluation of the quality of the water-guided laser water jet. The invention realizes the detection of the quality of the laser water jet, performs quantitative evaluation of the quality of the laser water jet, and more accurately judges whether the current laser water jet is suitable for processing.

Description

Technical Field

[0001] The invention belongs to the technical field of water-guided lasers and relates to a water jet quality detection device and a detection method for water-guided lasers. Background Art

[0002] Water-guided laser technology is an advanced laser processing technology. Its principle is to use the phenomenon of total reflection of laser at the interface between water and air to couple the laser beam into a fine water jet, and maintain an extremely high laser energy density in the water jet to achieve material processing. Due to the addition of water flow, the water-guided laser can not only take away the processing debris and ensure the clean processing area, but also cool the cutting area, reduce the thermal deformation and thermal damage of the material, and form advantages such as high processing accuracy, high cutting quality, green, high efficiency, and no damage. The processing water jet formed by coupling directly affects the processing quality, but there is currently no unified and stable evaluation method for processing water jets. Most of them are indirectly evaluated by calculating the coupling efficiency. This method is not direct enough, and it is necessary to measure the power before coupling and the power after coupling separately and then calculate them. There are many steps and complicated operations. Therefore, we propose a method to directly detect and evaluate the water jet based on its own characteristics to improve work efficiency. Summary of the invention

[0003] The technical solution adopted by the present invention to solve the technical problem is: a water-guided laser water jet quality detection device, including: a coupling system, a laser water jet, a first detector, and a second detector. The coupling system couples the laser beam in a high-pressure water jet to form a laser water jet. The first detector and the second detector are both annular. The inner rings of the first detector and the second detector are evenly surrounded by a plurality of photosensitive sheets. The photosensitive sheets are used to sense the total reflection state of the outer circumference of the laser water jet and convert the sensed information into electrical signals and upload them; the first detector and the second detector are respectively arranged around the outside of the laser water jet, and the photosensitive parts of the photosensitive sheets are respectively radially facing the outer circumference of the laser water jet; the first detector and the second detector are arranged in parallel.

[0004] Preferably, the number of photosensitive sheets on the first detector and the second detector is three to twelve.

[0005] More preferably, the photosensitive film includes a photosensitive chip.

[0006] More preferably, the number of photosensitive sheets on the first detector and the second detector is four to eight.

[0007] Preferably, the distance between the first detector and the second detector along the laser water jet emission direction is 8 mm to 15 mm.

[0008] Preferably, the first detector, the second detector and the laser water jet have the same rotation axis.

[0009] The present invention also discloses a water jet quality detection method using a water-guided laser. The detection method is used for the above-mentioned water jet quality detection device. The specific steps of the detection method include:

[0010] Step 1: The first detector is set below the laser water jet emission port of the coupling system, and the optical signal of the laser water jet at different azimuths at the height of the first detector is measured through the photosensitive film, and the amplitude and frequency of the optical signal remain similar;

[0011] Step 2: Set the second detector below the first detector, and measure the light signals at different azimuths at the height of the second detector through the photosensitive sheet; the amplitude of the light signals at different heights should be attenuated;

[0012] Step 3: comparing the characteristic value ɑ between optical signals at different directions at the same height and the characteristic value β between optical signals at the same directions at different heights in step 1 and step 2;

[0013] Step 4: When α and β are both greater than the first threshold, it means that the scattered light signals are similar in both the cross section of the laser water jet and the longitudinal propagation direction, indicating that the laser water jet has high quality;

[0014] Step 5: When ɑ is less than the first threshold and β is greater than the first threshold, it means that the laser water jet has uneven quality and uneven energy distribution in the cross section, but still propagates stably in the longitudinal direction, indicating that processing can be carried out, but the processing quality needs to be improved;

[0015] Step 6: When β is greater than the second threshold and less than the first threshold, it means that the longitudinal propagation of the laser water jet is unstable and the laser water jet cannot be used for processing for a long time; in addition, when β is less than the second threshold, it means that the laser water jet propagation is unstable and cannot be used for processing.

[0016] Preferably, in step 4, step 5, and step 6, the first threshold value ranges from 0.71 to 0.89, and the second threshold value ranges from 0.51 to 0.69; different threshold values ​​are selected according to different processing accuracy requirements. Under the premise of meeting the processing accuracy, the threshold should not be set too high to achieve the best cost-effectiveness.

[0017] More preferably, in step 4, step 5, and step 6, the first threshold value is 0.8, and the second threshold value is 0.6.

[0018] Preferably, step 4, step 5 and step 6 further include a third threshold, a fourth threshold and a fifth threshold, and the third threshold, the fourth threshold and the fifth threshold are all between the first threshold and the second threshold, and the third threshold, the fourth threshold and the fifth threshold distinguish the characteristic value ɑ between optical signals in different directions at the same height and the characteristic value β between optical signals in the same direction at different heights in more detail, thereby forming a more detailed water jet quality grade.

[0019] The beneficial effects of the present invention are:

[0020] The present invention arranges a plurality of detectors at different heights in the direction of the laser water jet, arranges a plurality of evenly distributed photosensitive sheets in the detector with the detection surface radially facing the direction of the laser water jet, and realizes quantitative evaluation of the quality of the water-guided laser water jet by detecting the real-time state of total reflection at different heights and angles; the present invention realizes the detection of the quality of the laser water jet, performs quantitative evaluation of the quality of the laser water jet, and more accurately judges whether the current laser water jet is suitable for processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a water jet quality inspection system diagram of a water-guided laser;

[0022] Figure 2 It is a schematic diagram of the detector and the photosensitive film;

[0023] Figure 3 This is a diagram of a water jet quality testing device.

[0024] Among them, 1. coupling system; 2. laser water jet; 3. first detector; 4. second detector; 5. photosensitive film; 301. fixing bracket; 302. supporting base plate; 303. host computer. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the relevant technologies in the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] refer to Figures 1 to 3The water jet quality detection device of water-guided laser includes: a coupling system 1, a laser water jet 2, a first detector 3, and a second detector 4. The coupling system 1 couples the laser beam in the high-pressure water jet to form the laser water jet 2. The first detector 3 and the second detector 4 are both annular. The inner rings of the first detector 3 and the second detector 4 are uniformly surrounded by a plurality of photosensitive sheets 5. The photosensitive sheets 5 are used to sense the total reflection state of the outer circumference of the laser water jet 2 and convert the sensed information into an electrical signal and upload it; the first detector 3 and the second detector 4 are respectively surrounded by Outside the laser water jet 2, the photosensitive parts of the photosensitive film 5 are radially opposite to the outer circumference of the laser water jet 2; the first detector 3 and the second detector 4 are arranged in parallel; the photosensitive film 5 on the first detector 3 and the second detector 4 monitors the total reflection state of the laser in the laser water jet 2 in real time, and the photosensitive film 5 can sense the total reflection state of the laser in the laser water jet 2 and convert the sensed light signal into an electrical signal. After processing these electrical signals, the stability parameters of the laser water jet 2 can be obtained, thereby realizing the detection of the stability of the laser water jet 2.

[0027] Furthermore, the number of photosensitive films 5 on the first detector 3 and the second detector 4 is three to twelve pieces each; the number of photosensitive films 5 on each detector is selected according to the actual processing accuracy requirements on site and the actual conditions of the product, equipment, and environment. The smaller the number, the larger the circular range angle of the laser water jet 2 detected by each photosensitive film 5, the lower the accuracy of the angle edge zone, and the lower the accuracy of the overall monitoring result. However, the minimum number of photosensitive films 5 is not less than three, that is, the monitoring angle of each photosensitive film 5 does not exceed 120°; when the number of photosensitive films 5 is more, the smaller the circular range angle of the laser water jet 2 detected by each photosensitive film 5, the higher the accuracy of the angle edge zone, and the higher the accuracy of the overall monitoring result. However, due to the small spatial position and calculation amount, the maximum number of photosensitive films 5 is not more than twelve, that is, the monitoring angle of each photosensitive film 5 is not less than 30°.

[0028] Furthermore, the photosensitive film 5 includes a photosensitive chip.

[0029] Furthermore, the number of photosensitive films 5 on the first detector 3 and the second detector 4 is four to eight. On the premise of ensuring accuracy, economic rationality and controllable computational complexity, the optimal number of photosensitive films 5 on each detector is four to eight.

[0030] Furthermore, the distance between the first detector 3 and the second detector 4 along the emission direction of the laser water jet 2 is 8 mm to 15 mm; the height difference between the detectors is determined by the surface shape of the workpiece, the processing depth and the effective processing length of the water-guided laser.

[0031] Furthermore, the first detector 3 and the second detector 4 rotate on the same axis as the laser water jet 2. When the detector rotates on the same axis as the laser water jet 2, since the photosensitive film 5 is evenly distributed around the inner circle of the detector, the distance between each detector and the periphery of the laser water jet 2 is closer, the detection error is smaller, and the detection accuracy is higher.

[0032] This specific embodiment also includes a water jet quality detection method using a water-guided laser. The detection method is used in the above-mentioned water jet quality detection device. The specific steps of the detection method include:

[0033] Step 1: The first detector 3 is set below the emission port of the laser water jet 2 of the coupling system 1, and the optical signal of the laser water jet 2 at different azimuths at the height of the first detector 3 is measured through the photosensitive film 5, and the amplitude and frequency of the optical signal remain similar;

[0034] Step 2: The second detector 4 is set below the first detector 3, and the light signals at different azimuths at the height where the second detector 4 is set are measured through the photosensitive film 5; the amplitudes of the light signals at different heights should be attenuated;

[0035] Step 3: comparing the characteristic value ɑ between optical signals at different directions at the same height and the characteristic value β between optical signals at the same directions at different heights in step 1 and step 2;

[0036] Step 4: When α and β are both greater than the first threshold, it means that the scattered light signals are similar in both the cross section of the laser water jet and the longitudinal propagation direction, indicating that the laser water jet has high quality;

[0037] Step 5: When ɑ is less than the first threshold and β is greater than the first threshold, it means that the laser water jet has uneven quality and uneven energy distribution in the cross section, but still propagates stably in the longitudinal direction, indicating that processing can be carried out, but the processing quality needs to be improved;

[0038] Step 6: When β is greater than the second threshold and less than the first threshold, it means that the longitudinal propagation of the laser water jet is unstable and the laser water jet cannot be used for processing for a long time; in addition, when β is less than the second threshold, it means that the laser water jet propagation is unstable and cannot be used for processing.

[0039] Furthermore, in step 4, step 5, and step 6, the first threshold value ranges from 0.71 to 0.89, and the second threshold value ranges from 0.51 to 0.69; different threshold values ​​are selected according to different processing accuracy requirements. Under the premise of meeting the processing accuracy, the threshold should not be set too high to achieve the best cost-effectiveness.

[0040] Furthermore, in step 4, step 5, and step 6, the first threshold value is 0.8, and the second threshold value is 0.6.

[0041] Furthermore, step 4, step 5, and step 6 also include a third threshold, a fourth threshold, and a fifth threshold, and the third threshold, the fourth threshold, and the fifth threshold are all between the first threshold and the second threshold, and the third threshold, the fourth threshold, and the fifth threshold distinguish the characteristic value ɑ between optical signals in different directions at the same height and the characteristic value β between optical signals in the same direction at different heights in more detail, thereby forming a more detailed water jet quality grade; when the processing types or specifications of the laser water jet 2 are various according to actual needs, multi-order thresholds can be established between the first threshold and the second threshold, and different quality grades of the laser water jet 2 for processing can be selected according to different processing requirements.

[0042] Example

[0043] In this embodiment, two detectors are arranged in parallel up and down, and four photosensitive sheets 5 are provided on each detector. The photosensitive sheets 5 are photosensitive chips, and the spacing between the two detectors is 10 mm. The laser in the laser water jet 2 will form a total reflection in the water jet, and the water jet acts as an optical fiber to transmit the laser. However, due to the instability of the laser water jet 2 and the change of laser intensity, the total reflection state of the laser will change, and the laser will dissipate and change nonlinearly during the transmission process. In this embodiment, the total reflection state of the laser is monitored in real time by the first detector 3 and the second detector 4, so as to detect the stability of the laser water jet 2.

[0044] The first detector 3 and the second detector 4 are a circular ring structure, and four photosensitive chips are attached to the inner wall of the ring. The photosensitive chip can sense the total reflection state of the laser and convert the sensed information into electrical signals. After processing these electrical signals, the stability parameters of the laser water jet 2 can be obtained. This embodiment combines high-pressure water with laser through the coupling system 1, so that the laser can form a stable total reflection in the high-pressure water, thereby improving the stability of the water jet. At the same time, this embodiment monitors the total reflection state of the laser in real time through the first detector 3 and the second detector 4, and monitors the stability of the water jet in real time, thereby realizing the quantitative evaluation of the quality of the water-guided laser microjet.

[0045] In this embodiment, the first detector 3 is placed 40 mm below the coupling system 1. Four photosensitive chips are placed equidistantly in the first detector 3. The optical signals of the laser water jet 2 at different azimuths at a certain height are measured by the four chips. The amplitudes and frequencies of these four groups of signals should remain similar. The second detector 4 is placed 10 mm below the first detector 3 to measure the scattered optical signals of the laser water jet 2 at another height. The amplitudes of optical signals at different heights should be attenuated. The characteristic values ​​ɑ between optical signals at different azimuths at the same height and the characteristic values ​​β between optical signals at the same azimuth at different heights are compared, specifically, the covariance, correlation coefficient, mean, and power spectrum are calculated. In this embodiment, the correlation coefficient is used as the characteristic value index. When ɑ and β are both greater than 0.8, it means that the scattered light signals are similar in both the cross section and the longitudinal propagation direction of the laser water jet 2, which means that the quality of the laser water jet 2 is very high and it can be defined as a first-level microjet. When ɑ is less than 0.8 and β is greater than 0.8, it means that the quality of the laser water jet 2 is uneven and the energy distribution is uneven in the cross section, but it still propagates stably in the longitudinal direction. At this time, it is defined as a second-level microjet, which means that it can be processed, but the processing quality may need to be improved. When β is greater than 0.6 and less than 0.8, it means that its longitudinal propagation is not stable and the laser water jet 2 cannot be used for processing for a long time. It is defined as a third-level microjet. In addition, when β is less than 0.6, it means that the propagation of the laser water jet 2 is very unstable and cannot be used for processing. It is defined as a fourth-level microjet. According to the detection and analysis of the optical signal of the laser water jet 2, the quantitative classification of the laser water jet 2 is realized, and whether the current laser water jet 2 is suitable for processing is accurately judged, thereby improving the processing efficiency and quality.

[0046] Example

[0047] In this embodiment, the first detector 3 and the second detector 4 are movably fixed on a vertical fixing bracket 301 , and the fixing bracket 301 is installed on a rectangular support base plate 302 . The first detector 3 and the second detector 4 are electrically connected to a host computer 303 , respectively.

[0048] In this embodiment, the position of the first detector 3 is fixed and the position of the second detector 4 is moved, so as to focus on analyzing and evaluating the quality and stability of the water jet in the longitudinal propagation.

[0049] Step 1: Fix the first detector 3 10 mm below the coupling system 1. There are 6 photosensitive chips on the back of the detector 3 distributed at equal intervals, which are used to detect light signals from six different directions.

[0050] Step 2: Fix the second detector 4 5 mm below the first detector 3 so that the initial distance between the second detector 4 and the first detector 3 is as small as possible;

[0051] Step 3: Turn on the laser, and the laser passes through the coupling system to form a high-energy laser water jet 2, which passes through the central axis of the first detector 3 and the second detector 4, and is collected and transmitted to the host computer 303 for analysis and processing;

[0052] Step 4: Move the second detector 4 downward at a uniform speed of 1 mm / s, change the position of the second detector 4 in real time, and compare and analyze the optical signal detected by the second detector 4 in real time with the optical signal detected by the first detector 3;

[0053] Step 5: When the characteristic value β between the two is less than 0.6, record the position information of the second detector 4 at this time, calculate the distance d between the two detectors to be 64mm, which is the effective processing length, and then combine the nozzle model to determine the current water jet quality. If the current nozzle length is 50 microns, then the effective processing length d is greater than 80mm for the first-level micro jet, which can be processed for a long time; the effective processing length d is greater than 60mm and less than 80mm for the second-level micro jet, which can be processed for a certain period of time; the effective processing length d is less than 60mm for the third-level micro jet, which cannot be used for processing.

[0054] In summary, the present invention realizes quantitative evaluation of the quality of water-guided laser water jet by arranging multiple detectors at different heights in the direction of laser water jet, arranging multiple uniformly distributed photosensitive sheets in the detector with the detection surface radially facing the direction of laser water jet, and detecting the real-time state of total reflection at different heights and angles. The present invention realizes the detection of laser water jet quality, quantitative evaluation of laser water jet quality, and more accurately judges whether the current laser water jet is suitable for processing, and has broad application prospects in the field of water-guided laser processing technology.

[0055] It should be emphasized that the above are only preferred embodiments of the present invention and do not limit the present invention in any form. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A water jet quality detection device using a water-guided laser, characterized in that: include: A coupling system (1), a laser water jet (2), a first detector (3), and a second detector (4), wherein the coupling system (1) couples a laser beam in a high-pressure water jet to form the laser water jet (2), the first detector (3) and the second detector (4) are both in the shape of a ring, and a plurality of photosensitive sheets (5) are evenly distributed around the inner rings of the first detector (3) and the second detector (4), and the photosensitive sheets (5) are used to sense the total reflection state of the outer circumference of the laser water jet (2) and convert the sensed information into an electrical signal and upload it; The first detector (3) and the second detector (4) are respectively arranged around the laser water jet (2), and the photosensitive parts of the photosensitive sheet (5) are respectively radially facing the outer circumference of the laser water jet (2); The first detector (3) and the second detector (4) are arranged in parallel.

2. The water jet quality detection device of water-guided laser according to claim 1 is characterized in that: The number of photosensitive sheets (5) on the first detector (3) and the second detector (4) is three to twelve.

3. The water jet quality detection device of water-guided laser according to claim 2 is characterized in that: The photosensitive sheet (5) comprises a photosensitive chip.

4. The water jet quality detection device of water-guided laser according to claim 2 is characterized in that: The number of photosensitive sheets (5) on the first detector (3) and the second detector (4) is four to eight.

5. The water jet quality detection device of water-guided laser according to claim 1 is characterized in that: The distance between the first detector (3) and the second detector (4) along the emission direction of the laser water jet (2) is 8 mm to 15 mm.

6. The water jet quality detection device of water-guided laser according to claim 1 is characterized in that: The first detector (3), the second detector (4) and the laser water jet (2) have the same rotation axis.

7. A water jet quality detection method using a water-guided laser, characterized in that: The detection method is used for any water-guided laser water jet quality detection device in claims 1 to 6, and the specific steps of the detection method include: Step 1: a first detector (3) is arranged below the emission port of the laser water jet (2) of the coupling system (1), and light signals of the laser water jet (2) at different azimuth angles at the height where the first detector (3) is arranged are measured through a photosensitive sheet (5), wherein the amplitude and frequency of the light signals remain similar; Step 2: The second detector (4) is arranged below the first detector (3), and the light signals at different azimuth angles at the height where the second detector (4) is arranged are measured through the photosensitive sheet (5); the amplitudes of the light signals at different heights should be attenuated; Step 3: comparing the characteristic value ɑ between optical signals at different directions at the same height and the characteristic value β between optical signals at the same directions at different heights in step 1 and step 2; Step 4: When α and β are both greater than the first threshold, it means that the scattered light signals are similar in both the cross section of the laser water jet and the longitudinal propagation direction, indicating that the laser water jet has high quality; Step 5: When ɑ is less than the first threshold and β is greater than the first threshold, it means that the laser water jet has uneven quality and uneven energy distribution in the cross section, but still propagates stably in the longitudinal direction, indicating that processing can be carried out, but the processing quality needs to be improved; Step 6: When β is greater than the second threshold and less than the first threshold, it means that the longitudinal propagation of the laser water jet is unstable and the laser water jet cannot be used for processing for a long time; in addition, when β is less than the second threshold, it means that the laser water jet propagation is unstable and cannot be used for processing.

8. The water jet quality detection method of water-guided laser according to claim 7 is characterized in that: In step 4, step 5 and step 6, the first threshold value ranges from 0.71 to 0.89, and in step 6, the second threshold value ranges from 0.51 to 0.

69.

9. The water jet quality detection method of water-guided laser according to claim 8 is characterized in that: In step 4, step 5 and step 6, the first threshold value is 0.8 and the second threshold value is 0.

6.

10. The water jet quality detection method of water-guided laser according to claim 7, characterized in that: Step 4, step 5 and step 6 further include a third threshold, a fourth threshold and a fifth threshold, and the third threshold, the fourth threshold and the fifth threshold are all between the first threshold and the second threshold. The third threshold, the fourth threshold and the fifth threshold distinguish the characteristic value ɑ between optical signals in different directions at the same height and the characteristic value β between optical signals in the same direction at different heights in more detail, thereby forming a more detailed water jet quality grade.

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