Laser drilling machine detection device and detection method

Abstract

The invention belongs to the technical field of laser drilling machines, and particularly relates to a laser drilling machine detection device and method.The laser drilling machine detection device comprises an optical detection module, a laser positioning module, a data processing unit and a closed-loop control module. The optical detection module comprises an industrial camera and a thermal infrared imager which are coaxial in light path. The optical detection module is used for collecting visible light images and temperature field distribution of a drilling area in real time. The laser positioning module comprises a displacement sensor integrated on the laser drilling machine and is used for monitoring three-dimensional coordinates of a laser focus in real time. The data processing unit is used for connecting the optical detection module and the laser positioning module. The closed-loop control module is based on the output signal of the data processing unit. According to the laser drilling machine detection device, the structural layout of the laser drilling machine detection device can be optimized, the real-time detection efficiency of the detection device can be improved, meanwhile, the product microdefect detection precision can be greatly improved, and therefore the product machining qualification rate can be remarkably increased.

Description

Technical Field

[0001] This invention belongs to the field of laser drilling machine technology, specifically relating to a laser drilling machine testing device and testing method. Background Technology

[0002] A laser drilling machine is a device that uses laser technology to drill holes. It can instantly penetrate the surface of materials using a high-power laser beam, creating precise and consistently high-quality small holes. It boasts advantages such as high efficiency, high precision, and automation, and is widely used in industries such as automotive, electronics, electrical appliances, construction, aerospace, and arts and crafts. After laser drilling is completed, the product needs to undergo hole inspection to ensure that parameters such as hole diameter and depth meet design requirements, thereby guaranteeing product quality and performance. Chinese patent CN117697187A discloses a drilling inspection device, method, and laser drilling machine. It mounts a camera near the optical axis of the laser drilling machine, allowing it to capture real-time images of the drilling process on the substrate as the laser drilling moves. Simultaneously, a processing module analyzes the captured images to detect any anomalies that may occur during processing, enabling real-time detection and calibration, which can meet certain usage requirements. However, this inspection device relies on offline coordinate measuring machine (CMM), resulting in low inspection efficiency and poor real-time performance. It also fails to address the issue of insufficient accuracy in identifying micro-defects.

[0003] Therefore, in order to address the above-mentioned technical problems, it is necessary to provide a laser drilling machine testing device and testing method.

[0004] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a laser drilling machine inspection device and inspection method, which can solve the problems mentioned above.

[0006] To achieve the above objectives, a specific embodiment of the present invention provides the following technical solution: A laser drilling machine inspection device includes: an optical inspection module, a laser positioning module, a data processing unit, and a closed-loop control module. The optical inspection module includes an industrial camera with a coaxial optical path and an infrared thermal imager, used to acquire visible light images and temperature field distribution of the drilling area in real time. The laser positioning module includes a displacement sensor integrated into the laser drilling machine, used to monitor the three-dimensional coordinates of the laser focus in real time. The data processing unit connects the optical inspection module and the laser positioning module. The closed-loop control module dynamically adjusts the laser power and scanning speed of the laser drilling machine based on the output signal of the data processing unit.

[0007] In one or more embodiments of the present invention, the industrial camera is equipped with a narrowband filter with a wavelength of 450-650nm, a sampling frequency of ≥2000fps, and a resolution of not less than 5 million pixels.

[0008] In one or more embodiments of the present invention, the displacement sensor is a confocal displacement sensor with a measurement accuracy of ≤±1μm and a response time of ≤10ms.

[0009] In one or more embodiments of the present invention, the data processing unit integrates a deep learning model, the training samples of which include 100,000 sets of borehole defect images, which can identify microcracks, slag residue and taper anomalies.

[0010] In one or more embodiments of the present invention, the data processing unit includes an image feature extraction subunit and a thermal field analysis subunit. The image feature extraction subunit is used to identify the borehole coordinates, borehole diameter and borehole wall roughness, and the thermal field analysis subunit is used to calculate the temperature gradient of the borehole area and the range of the heat-affected zone.

[0011] In one or more embodiments of the present invention, the closed-loop control module establishes a process parameter mapping table, wherein the mapping relationship satisfies: P_{new}=k_1\cdot\DeltaD+k_2\cdot\frac{dT}{dt} Where P_{new} is the adjusted laser power, ΔD is the aperture deviation, dT / dt is the temperature rise rate, and k1 and k2 are material correlation coefficients.

[0012] A detection method for a laser drilling machine detection device includes the following steps: S1. Synchronously trigger laser pulses and image acquisition to obtain high-speed sequence images of the drilling process; S2. Extract the sub-pixel coordinates of the hole edges in a single frame image and fit the actual hole diameter value D_actual; S3. Compare with the design value D_design. If |D_actualD_design|>threshold δ, where δ=3μm, start the closed-loop control module to adjust the laser energy density.

[0013] In one or more embodiments of the present invention, step S2 employs an improved Canny-Zernike edge detection algorithm, specifically including the following steps: S201. Perform non-uniform illumination compensation on the image; S202. The Zernike moment orthogonal polynomial is used to calculate the sub-pixel offset of the edge. S203: Edge positions are determined by Gaussian surface fitting, with a positioning accuracy of 0.1 pixels.

[0014] In one or more embodiments of the present invention, a heat-affected zone assessment is performed after S3, specifically including the following steps: S301. Obtain the temperature distribution matrix T(x, y) from the infrared thermal imager; S302. Calculate the area S_HAZ of the region exceeding the material recrystallization temperature T_rec; S303. If S_HAZ > the design allowable value S_max, reduce the laser pulse frequency by 10%-25%.

[0015] In one or more embodiments of the present invention, in S302, the T_rec is dynamically set according to the material: If a metallic material is used, then T_rec = 0.4 × T_melt, where T_melt is the melting point of the material; If a polymer material is used, then T_rec = T_glass - 50℃, where T_glass is the glass transition temperature.

[0016] Compared with the prior art, the laser drilling machine inspection device and inspection method of the present invention can optimize the structural layout of the laser drilling machine inspection device, thereby improving the real-time inspection efficiency of the inspection device and significantly improving the detection accuracy of micro-defects in products, thus significantly improving the product processing qualification rate. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a system block diagram of a laser drilling machine detection device according to an embodiment of the present invention; Figure 2 This is a flowchart of a detection method for a laser drilling machine detection device according to an embodiment of the present invention; Figure 3 This is a diagram showing the application detection results in one embodiment of the present invention. Detailed Implementation

[0019] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0020] like Figure 1 As shown, an embodiment of the laser drilling machine inspection device of the present invention includes an optical inspection module, a laser positioning module, a data processing unit, and a closed-loop control module. The optical inspection module includes an industrial camera with a coaxial optical path and an infrared thermal imager, used to acquire visible light images and temperature field distribution of the drilling area in real time. The laser positioning module includes a displacement sensor integrated into the laser drilling machine, used to monitor the three-dimensional coordinates of the laser focus in real time. The data processing unit connects the optical inspection module and the laser positioning module. The closed-loop control module, based on the output signal of the data processing unit, dynamically adjusts the laser power and scanning speed of the laser drilling machine.

[0021] The industrial camera is equipped with a narrowband filter with a wavelength of 450-650nm, a sampling frequency of ≥2000fps, and a resolution of no less than 5 million pixels.

[0022] In addition, industrial cameras and infrared thermal imagers share a beam splitter prism, which can significantly improve the optical path overlap.

[0023] Specifically, the displacement sensor is a confocal displacement sensor with a measurement accuracy of ≤±1μm and a response time of ≤10ms.

[0024] like Figure 1 As shown, the data processing unit integrates a deep learning model. The training samples of the deep learning model include 100,000 sets of borehole defect images, which can identify microcracks, slag residue, and taper anomalies.

[0025] Preferably, the identification threshold for microcracks is 5 μm, the identification threshold for slag residue is 3 μm, and the identification threshold for taper anomalies is ±0.5°.

[0026] like Figure 1As shown, the data processing unit includes an image feature extraction subunit and a thermal field analysis subunit. The image feature extraction subunit is used to identify the borehole coordinates, borehole diameter, and borehole wall roughness, while the thermal field analysis subunit is used to calculate the temperature gradient and heat-affected zone range of the borehole area.

[0027] The closed-loop control module establishes a process parameter mapping table, and the mapping relationship satisfies: P_{new}=k_1\cdot\DeltaD+k_2\cdot\frac{dT}{dt} Where P_{new} is the adjusted laser power, ΔD is the aperture deviation, dT / dt is the temperature rise rate, and k1 and k2 are material correlation coefficients.

[0028] like Figure 2 As shown, a detection method for a laser drilling machine detection device includes the following steps: S1. Synchronously trigger laser pulses and image acquisition to obtain high-speed sequence images of the drilling process; S2. Extract the sub-pixel coordinates of the hole edges in a single frame image and fit the actual hole diameter value D_actual; S3. Compare with the design value D_design. If |D_actualD_design|>threshold δ, where δ=3μm, start the closed-loop control module to adjust the laser energy density.

[0029] S2 employs an improved Canny-Zernike edge detection algorithm, specifically including the following steps: S201. Perform non-uniform illumination compensation on the image; S202. The Zernike moment orthogonal polynomial is used to calculate the sub-pixel offset of the edge. S203: Edge positions are determined by Gaussian surface fitting, with a positioning accuracy of 0.1 pixels.

[0030] In addition, a heat-affected zone assessment is performed after S3, which includes the following steps: S301. Obtain the temperature distribution matrix T(x, y) from the infrared thermal imager; S302. Calculate the area S_HAZ of the region exceeding the material recrystallization temperature T_rec; S303. If S_HAZ > the design allowable value S_max, reduce the laser pulse frequency by 10%-25%.

[0031] Specifically, in S302, T_rec is dynamically set according to the material: If a metallic material is used, then T_rec = 0.4 × T_melt, where T_melt is the melting point of the material; If a polymer material is used, then T_rec = T_glass - 50℃, where T_glass is the glass transition temperature.

[0032] Application Example 1 Inspection of PCB micro-hole fabrication: Material: FR4 epoxy glass cloth laminate Laser parameters: wavelength 355nm, pulse width 20ns Experimental results are as follows Figure 3 As shown, according to Figure 3 As can be seen, the detection device used in this application can perform real-time detection of PCB micro-holes, which can not only significantly reduce hole diameter errors, but also control the heat-affected zone.

[0033] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0034] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A laser drilling machine detection device, characterized by, The application relates to a laser drilling system, comprising: an optical detection module comprising an industrial camera and an infrared thermal imager with coaxial optical paths, which is used for real-time acquisition of visible light images and temperature field distribution of a drilling area; a laser positioning module comprising a displacement sensor integrated in a laser drilling machine, which is used for real-time monitoring of three-dimensional coordinates of a laser focal point; a data processing unit connected to the optical detection module and the laser positioning module; a closed-loop control module based on output signals of the data processing unit, which is used for dynamic adjustment of laser power and scanning speed of the laser drilling machine.

2. A laser drilling machine detection device according to claim 1, wherein, The industrial camera is equipped with a narrowband filter with a wavelength of 450-650 nm, a sampling frequency of no less than 2000 fps and a resolution of no less than 5 million pixels.

3. The detection device for a laser drilling machine according to claim 1, wherein The displacement sensor is a confocal displacement sensor with a measurement accuracy of no more than plus or minus 1 mu m and a response time of no more than 10 ms.

4. The detection device for a laser drilling machine according to claim 1, wherein, The data processing unit integrates a deep learning model, training samples of the deep learning model contain 100,000 groups of drilling defect images, and the deep learning model can identify microcracks, slag residues and abnormal tapers.

5. The detection device for a laser drilling machine according to claim 1, wherein, The data processing unit comprises an image feature extraction subunit and a thermal field analysis subunit, the image feature extraction subunit is used for identifying hole position coordinates, hole diameter size and hole wall roughness, and the thermal field analysis subunit is used for calculating a temperature gradient of the drilling area and a range of a heat affected zone.

6. The detection device for a laser drilling machine according to claim 1, wherein, The closed-loop control module establishes a process parameter mapping table, and a mapping relationship meets the following formula: P_new=k1*DeltaD+k2*dT / dt, wherein P_new is adjusted laser power, DeltaD is a hole diameter deviation, dT / dt is a temperature rise rate, and k1 and k2 are material-related coefficients. The application further discloses a laser drilling method, comprising the following steps: S1, synchronously triggering a laser pulse and image acquisition to obtain high-speed sequence images of a drilling process; 7. A detection method of the detection device of the laser drilling machine according to any one of claims 1 to 6, characterized in that, S2, extracting sub-pixel coordinates of a hole edge in a single image to fit an actual hole diameter value D_actual; S3, comparing the actual hole diameter value D_actual with a design value D_design, and if an absolute value of a difference between the actual hole diameter value D_actual and the design value D_design is greater than a threshold value delta, wherein the threshold value delta is 3 mu m, a closed-loop control module is started to adjust laser energy density. The S2 adopts an improved Canny-Zernike edge detection algorithm, and specifically comprises the following steps: S201, performing non-uniform illumination compensation on an image; 8. The detection method of a detection device of a laser drilling machine according to claim 7, characterized in that, S202, calculating edge sub-pixel offset by using Zernike orthogonal polynomials; S203, determining an edge position by Gaussian surface fitting, and positioning accuracy reaches 0.1 pixels. After the S3, a heat affected zone is evaluated, and the evaluation specifically comprises the following steps: S301, obtaining a temperature distribution matrix T(x, y) from an infrared thermal imager; 9. The detection method of the detection device of the laser drilling machine according to claim 7, characterized in that, S302, calculating an area S_HAZ of a region exceeding a material recrystallization temperature T_rec; S303, if the area S_HAZ is greater than a design allowable value S_max, reducing a laser pulse frequency by 10%-25%. In the S302, the T_rec is dynamically set according to a material: If a metal material is used, the T_rec=0.4*T_melt, and T_melt is a melting point of the material.

10. The detection method of the detection apparatus of the laser drilling machine according to claim 9, wherein, ​ ​ If a polymeric material is used, T_rec = T_glass - 50°C, T_glass being the glass transition temperature.

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