KR20230166973A - Laser welding monitoring system - Google Patents

Abstract

The laser welding monitoring system includes a work piece; a scanner configured to move in at least one axis direction to radiate a laser beam toward the work piece; A beam monitoring unit configured to monitor the quality of a laser beam using emitted light from a light source and detect contamination or damage to the optical system; a first sensor unit configured to monitor output power of the laser beam using the emitted light; and a second sensor unit configured to monitor welding abnormalities of the work piece using reflected light reflected from the work piece.

Description

Laser welding monitoring system

The present invention relates to a laser welding monitoring system, and more specifically, to a system that detects welding abnormalities using a laser beam.

Lasers are often used for welding as a non-contact energy source that requires minimal heat input. In particular, low-power pulsed lasers, which exhibit peak power with a small spot size, can heat materials above their melting point without dramatically increasing the temperature adjacent to the weld pool. Advanced features such as pulse shaping and laser power feedback have further improved solid-state lasers by providing increased control of laser power. However, despite these advanced features, predictions of laser-material interaction were not successful. Therefore, developing a reliable and easy-to-use laser welding monitoring system has been challenging.

Due to the critical nature of laser-material interaction for prediction, it is sometimes difficult to analyze monitored weld characteristics to distinguish good and bad welds. Moreover, complex pattern processing and/or advanced mathematical techniques are often used to analyze the taken profiles, which further complicates the analysis and processing process. Because of the difficulties associated with conventional monitoring techniques and analysis, users often do not understand monitoring procedures and instead rely solely on system developers to produce a system that meets their process development and/or process control needs.

In this regard, registered patent 10-1007724B1 provides a laser welding monitoring system that can evaluate the welding quality of welded areas using a pulse laser. The system includes one or more sensors capable of acquiring welding characteristics of a weld using the pulsed laser. The welding properties have various properties. The system also includes data collection and processing devices employed to store and analyze weld characteristics. The user first performs multiple welds to obtain one or more weld characteristics for each weld. The user then determines the weld quality of each weld and runs one or more of a series of algorithms relating the attributes to one or more weld characteristics for each weld to produce a single value output for the relevant attributes. A user selects an attribute representation of weld quality by correlating the single value output of the one or more algorithms with the weld characteristics of the weld.

However, the problem is that it is difficult to measure factors that may affect beam quality (contamination, damage, etc.) by measuring the 2D image, shape, diameter, and center position of the beam in real time because it cannot analyze the emitted light, which is the laser signal. There is.

Additionally, published patent 10-2013-0021343 relates to a real-time laser welding monitoring system and a laser micro-welding processing device. More specifically, the reflected light reflected during laser welding is obtained separately into infrared and ultraviolet signals, and the welding condition in terms of laser power, amount of heat input, keyhole creation and penetration degree, etc. is analyzed from each signal. In addition, it relates to a real-time laser welding monitoring system and a laser micro-welding processing device that can improve the quality of welding processing by effectively spraying processing gas on the material. However, the problem is that it is difficult to measure factors that may affect beam quality (contamination, damage, etc.) by measuring the 2D image, shape, diameter, and center position of the beam in real time because it cannot analyze the emitted light, which is the laser signal. There is.

Meanwhile, registered patent 10-1007724B1 and published patent 10-2013-0021343 both perform welding monitoring using only reflected light generated during welding, so there is a problem in that detection of welding abnormalities is affected by the surrounding environment.

Meanwhile, the existing laser welding monitoring system that uses only reflected light can only detect abnormalities during welding, but there is a problem in that it is difficult to distinguish whether these abnormalities are caused by deterioration in the quality of the welding beam or if the abnormal phenomenon occurred during actual welding.

The present invention aims to solve the above-mentioned problems and other problems. The present invention relates to a laser welding monitoring system and is intended to provide a system for detecting welding abnormalities using a laser beam.

In addition, the present invention relates to a laser welding monitoring system, and is intended to perform monitoring by including emitted light in addition to the existing welding monitoring system using only reflected light.

In addition, the present invention is intended to accurately distinguish not only an abnormal phenomenon during welding, but also whether the abnormal phenomenon is a problem of deterioration in the quality of the welding beam or whether the abnormal phenomenon occurred during actual welding.

In addition, the present invention is intended to effectively control and improve laser welding quality by using this laser welding monitoring system using both emitted and reflected light.

In addition, the present invention is intended to accurately measure factors that may affect beam quality by measuring the 2D image, shape, diameter, and center position of the beam in real time.

The laser welding monitoring system according to the present specification includes a work piece; a scanner configured to move in at least one axis direction to radiate a laser beam toward the work piece; A beam monitoring unit configured to monitor the quality of a laser beam using emitted light from a light source and detect contamination or damage to the optical system; a first sensor unit configured to monitor output power of the laser beam using the emitted light; and a second sensor unit configured to monitor welding abnormalities of the work piece using reflected light reflected from the work piece.

According to an embodiment, the beam monitoring unit and the first sensor unit are provided in a first structure coupled to a lower end portion of the scanner, and the second sensor unit is coupled to one side area of the scanner. It may be provided in a second structure.

According to an embodiment, the scanner includes an optical fiber light source disposed in an upper area of the scanner and configured to generate the laser beam so that the emitted light travels in a downward direction; a first mirror configured to separate the emitted light into first reflected light reflected in a horizontal direction and first transmitted light transmitted in a downward direction; and a galvano mirror configured to change the direction of travel of the first reflected light. Light passing through the galvano mirror may be reflected at a welding point of the work piece and pass through the galvano mirror to form second reflected light. The second reflected light may be configured to pass through the first mirror.

According to an embodiment, the second structure includes: a second mirror provided inside the CCD camera, which is the second structure, and disposed between the first mirror and the first sensor unit; and a second sensor unit disposed at one side of the CCD camera and configured to monitor welding abnormalities of the work piece using the second reflected light passing through the first mirror and the second mirror. there is. The second sensor unit may be provided in the post-radiation acquisition unit of the second structure.

According to an embodiment, the first structure includes a third mirror configured to separate the first transmitted light into a third reflected light reflected in a horizontal direction and a third transmitted light transmitted in a downward direction; The beam monitoring unit coupled to one side area of the first structure and configured to monitor the quality of the laser beam using the third reflected light reflected from the third mirror and detect contamination or damage to the optical system; and a first sensor unit coupled to a lower end of the first structure and configured to monitor output power of the laser beam. The first sensor unit may be provided in the laser input beam acquisition unit of the first structure.

According to an embodiment, the beam monitoring unit detects the two-dimensional image and distribution of the laser beam, measures and stores the shape of the laser beam, checks the diameter and beam center position of the laser beam, and It may be configured to detect contamination or damage to the optical system by detecting factors that affect its quality.

According to an embodiment, the first sensor unit and the second sensor unit may be configured to detect light with a wavelength of 350 nm to 1100 nm.

According to an embodiment, the third mirror may be disposed between the first mirror and the first sensor unit. The first mirror may be disposed inclined in a direction of 45 degrees with respect to the horizontal plane, and the third mirror may be disposed in a form inclined in a direction of -45 degrees with respect to the horizontal plane. The first sensor unit may be configured to monitor the output power of the laser beam by receiving the third transmitted light that has transmitted through the third mirror.

According to an embodiment, the galvano mirror is disposed in an area on the other side of the first mirror, and is configured to form a first refracted light in which the first reflected light reflected from the first mirror is refracted by a predetermined angle. No mirror; and a second galvano mirror disposed in a lower area on the other side of the first galvano mirror and configured to form the first refracted light into second refracted light in a downward direction.

According to an embodiment, the second sensor unit may monitor the reflected power of the laser beam by receiving the third reflected light reflected from the third mirror. The laser welding monitoring system may further include a control unit configured to detect welding abnormalities including gaps, focus changes, foreign matter, and folding phenomena based on the reflected power. The control unit may detect a welding abnormality based on the difference between the output power monitored by the first sensor unit and the reflected power monitored by the second sensor unit. The welding abnormality may include erroneous emission of the laser beam, emission at an abnormal position, and defective jig coupling.

According to an embodiment, the control unit sets the image of the laser beam measured on the welded product in a normal state as a reference image, compares the image of the laser beam measured on the work piece with the reference image, and determines the quality of the laser beam. can be monitored and contamination or damage to the optical system can be detected.

According to an embodiment, the control unit acquires time series data of reflected light measured from a welded product in a normal state, performs statistical and artificial intelligence-based learning using the time series data of the reflected light, and based on the results of the learning. It is possible to set a threshold value associated with a normal range and determine whether there is a welding abnormality in the work piece based on the threshold value.

According to an embodiment, the controller monitors the first reflected voltage associated with the reflected power by applying first pulses having a first voltage to the work piece in a first time interval, and monitors the first reflected voltage associated with the reflected power and the second pulse following the first time interval. Monitoring the second reflected voltage associated with the reflected power by applying second pulses having a second voltage greater than the first voltage to the work piece over a 2-time period, and adjusting the first and second reflected voltages to the first reflected voltage and the second reflected voltage. Based on this, welding abnormalities of the work piece can be detected.

According to at least one of the embodiments of the present invention, a system for detecting welding abnormalities using a laser beam can be provided.

According to at least one of the embodiments of the present invention, a laser welding monitoring system that monitors by including emitted light in addition to the existing welding monitoring system using only reflected light can be provided.

Existing laser welding monitoring systems that use only reflected light can only detect abnormalities during welding, but according to at least one embodiment of the present invention, not only abnormal phenomena during welding but also whether the abnormal phenomenon is actually a problem of deterioration of the quality of the welding beam is a problem. It is possible to accurately distinguish whether an abnormality occurred during welding.

According to at least one of the embodiments of the present invention, it is possible to solve the problem that it takes a lot of money and time to improve welding quality because it is difficult to determine the exact cause of the problem.

According to at least one of the embodiments of the present invention, laser welding quality control and improvement can be effectively performed using this laser welding monitoring system using both emitted and reflected light.

According to at least one of the embodiments of the present invention, laser welding quality control and improvement can be effectively performed using this laser welding monitoring system using both emitted and reflected light.

According to at least one of the embodiments of the present invention, contamination, damage, etc., which are factors that can affect beam quality, can be accurately measured by measuring the 2D image, shape, diameter, and center position of the beam in real time using emitted light. there is.

According to at least one of the embodiments of the present invention, abnormal phenomena occurring during laser welding can be systematically managed using a LBAD (Laser Beam Anomaly Detection) system that uses both emitted and reflected light, contributing to improving product competitiveness. You can.

1 shows the configuration of a laser welding monitoring system according to the present specification.
Figure 2 shows the mechanism structure of the laser welding monitoring system of Figure 1.
FIG. 3 is a block diagram showing each configuration of the laser welding monitoring system of FIG. 1.
Figure 4 shows an example of detecting an abnormal state of a welded portion by measuring a post-radiation beam using an input beam having pulses dynamically configured for each time section.
Figure 5 shows the results of detecting the power value of the post-radiation beam while changing the power value of the input beam within a time period in the laser welding monitoring system according to the present specification.
Figure 6 shows a specific UI screen displayed on the display of the control device to check the beam image, laser input beam, and post-radiation beam in an embodiment.

It should be noted that the technical terms used in this specification are only used to describe specific embodiments and are not intended to limit the present invention. Additionally, as used herein, singular expressions include plural expressions, unless the context clearly dictates otherwise. The suffixes “module” and “part” for components used in the following description are given or used interchangeably only for the ease of writing the specification, and do not have distinct meanings or roles in themselves.

As used herein, “consists of.” or “including.” Terms such as these should not be construed as necessarily including all of the various components or steps described in the specification, and some of the components or steps may not be included, or additional components or steps may be included. It should be interpreted to include more.

Additionally, when describing the technology disclosed in this specification, if it is determined that a detailed description of a related known technology may obscure the gist of the technology disclosed in this specification, the detailed description will be omitted.

In addition, the attached drawings are only for easy understanding of the embodiments disclosed in this specification, and the technical idea disclosed in this specification is not limited by the attached drawings, and all changes included in the spirit and technical scope of the present invention are not limited. , should be understood to include equivalents or substitutes. In addition, each embodiment described below, as well as a combination of embodiments, are changes, equivalents, or substitutes included in the spirit and technical scope of the present invention, and of course, may fall within the spirit and technical scope of the present invention. .

Hereinafter, the laser welding monitoring system according to the present specification will be described in detail with reference to the attached drawings. Since the laser welding monitoring system detects abnormalities in the welding area using a laser beam, it may be referred to as a Laser Beam Anomaly Detection (LABD) system.

Laser welding uses high speed and high energy, making it difficult to directly observe defects and abnormalities in the product during welding. Accordingly, various methods of laser welding monitoring systems are being developed, and the LBAD system according to the present invention can be one of them.

The present invention relates to a laser welding monitoring system, and is characterized by monitoring by including emitted light in addition to the existing welding monitoring system using only reflected light. In the emitted light, which is the original laser signal, the 2D image, shape, diameter, and center position of the beam are measured in real time to measure factors that may affect beam quality (contamination, damage, etc.). Abnormalities (power, gap, focus changes, and foreign matter/folding) are detected during welding using reflected light that reflects the phenomenon of the weld zone.

This LBAD system can be applied to all scanner types in laser welding, so it has a wide range of use. In this regard, Figure 1 shows the configuration of a laser welding monitoring system according to the present specification.

Referring to Figure 1, the laser welding monitoring system includes a work piece (10); It may be configured to include a scanner 100, a beam monitoring unit 200, a first sensor unit 300, and a second sensor unit 400. The beam monitoring unit 200, first sensor unit 300, and second sensor unit 400 may be referred to as a first monitoring unit, a second monitoring unit, and a third monitoring unit, respectively.

The work piece 10 is an object for detecting welding abnormalities and is configured to allow welding to occur in a certain area. The scanner 100 may be configured to move in at least one axis direction so that a laser beam radiates toward the work piece 10.

The beam monitoring unit 200 may be configured to monitor the quality of a laser beam using emitted light from a light source 101 and detect contamination or damage to the optical system. The first sensor unit 300 may be configured to monitor the output power of the laser beam using the emitted light from the light source 101. The second sensor unit 400 may be configured to monitor welding abnormalities of the work piece 10 using reflected light reflected from the work piece 10.

The characteristics and operation of the laser welding monitoring system according to the present invention, that is, the Laser Beam Anomaly Detection (LBAD) system, can be summarized as follows. If the LBAD system is not considered when initially installing a laser welder, interference with surrounding areas may occur. An LBAD system that detects welding anomalies by using an optical fiber (fiber optic) structure where the light source acts as an interference unit and each structure of the scanner of the LBAD system prevents interference between the light source and each structure can be applied.

In an LBAD system using a laser beam, the LBAD system can be implemented using not only the amount of reflected light but also the image of the laser beam and the amount of emitted light. The amount of reflected light may include reflected light from ultraviolet (UV) and near infrared (NIR) rays in addition to reflected light from the laser light source. The laser beam abnormality detection (LBAD) system according to the present invention can detect welding abnormalities using both emitted light and reflected light. Specifically, the LBAD system can detect welding abnormalities in a work piece by acquiring light quantity time series data using one emitted light and three reflected lights.

The beam monitoring unit 200, the first sensor unit 300, and the second sensor unit 400 may be placed in a specific area of the scanner 100. In this regard, Figure 2 shows the mechanical structure of the laser welding monitoring system of Figure 1.

Referring to FIG. 2, the scanner 100 may be configured to include its own mechanical structure and a first structure 1100 and a second structure 1200 coupled thereto. The first structure 1100 may be provided with a beam monitoring unit 200 and a first sensor unit 300 that acquires a laser input beam. Since the first structure 1100 acquires and measures beam images, the first structure 1100 may be equipped with a beam image camera. A second sensor unit 400 that acquires a back reflection beam may be provided in the second structure 1200.

1 and 2, the beam monitoring unit 200 and the first sensor unit 300 may be provided in the first structure 1100 coupled to the lower end portion of the scanner 100. . The second sensor unit 500 may be provided in the second structure 1200 coupled to one side area of the scanner 100. Therefore, the laser beam abnormality detection system according to the present specification can be implemented as a system that combines the hardware module of the beam monitoring system using emitted light and the monitoring system using reflected light.

The scanner 100 may be configured to include a light source 101, a collimator 102, a first mirror 110, and a galvano mirror 120. The light source 101 may be implemented as an optical fiber light source, but is not limited thereto. The light source 101 may be placed in the upper area of the scanner 100. The light source 101 may be formed so that a portion of the light source 101 is exposed to the upper area of the upper plate of the scanner 100. The light source 101 may be configured to generate a laser beam so that the emitted light travels downward. The collimator 102 may be configured to allow incident light (outgoing light) emitted from the light source 101 to proceed in parallel and enter the first mirror 110 .

The first mirror 110 may be configured to separate the emitted light into first reflected light that is reflected in the horizontal direction and first transmitted light that is transmitted in the downward direction. The first mirror 110 may be formed to be inclined at a predetermined angle with respect to the horizontal plane. For example, the first mirror 110 may be formed to be inclined at a 45 degree angle with respect to the horizontal plane, but is limited thereto and may be formed at a different angle depending on the application. The first mirror 110 may be implemented as a high resolution (HR) mirror with a resolution above a critical level.

The galvano mirror 120 may be configured to change the direction of travel of the first reflected light. Light passing through the galvano mirror 120 may be reflected at a welding point of the work piece 10 and pass through the galvano mirror 120 to form second reflected light. The second reflected light may be configured to pass through the first mirror 110.

The scanner 100 may be configured to further include a lens 171 and glass 172. The lens 171 may be implemented as a scanning lens such as an F-theta lens. The lens 171 may be configured to detect the surface shape, shape, and surface roughness of the work pieces 10 and 10b for each sub-area. The glass 172 may be configured to cover the lenses 171 and 171b to protect the glasses 172 and 172b.

The second structure 1200 may be configured to include a second mirror 130 and a second sensor unit 400. The second mirror 130 may be provided inside the CCD camera, which is the second structure 1200. The second mirror 130 may be disposed between the first mirror 110 and the first sensor unit 300. The second sensor unit 400 may be disposed in one area of the CCD camera, which is the second structure 1200. The second sensor unit 400 may be configured to monitor welding abnormalities of the work piece 10 using the second reflected light passing through the first mirror 110 and the second mirror 130. The second sensor unit 400 may be provided in a back radiation acquisition unit of the second structure 1200.

The first structure 1100 may be configured to include a third mirror 140, a beam monitoring unit 200, and a first sensor unit 300.

The third mirror 140 may be configured to separate the first transmitted light into the third transmitted light that is reflected in the horizontal direction and the third transmitted light that is transmitted in the downward direction. The beam monitoring unit 200 may be coupled to one side area of the first structure 1100. The beam monitoring unit 200 may monitor the quality of the laser beam using the third reflected light reflected from the third mirror 140. The beam monitoring unit 200 may be configured to monitor the quality of the laser beam using the third reflected light and detect contamination or damage to the optical system.

The first sensor unit 300 may be coupled to the lower end of the first structure 1100. The first sensor unit 300 may be configured to monitor the output power of the laser beam. The first sensor unit 300 may be provided in a laser beam acquisition unit of the first structure 1100.

The beam monitoring unit 200 may be configured to monitor a beam profile, such as beam quality, by applying an image-based algorithm. The beam monitoring unit 200 may be referred to as a beam profiler.

The beam monitoring unit 200 may be configured to detect a two-dimensional image and distribution of a laser beam, and measure and store the shape of the laser beam. The beam monitoring unit 200 may be configured to check the diameter and beam center position of the laser beam. The beam monitoring unit 200 may be configured to detect contamination or damage to the optical system by detecting factors that affect the quality of the laser beam.

The first sensor unit 300 may be implemented as a single sensor. The first sensor unit 300 may be configured to detect light of a wide band wavelength. The first sensor unit 300 may be configured to detect light with a wavelength of 350 nm to 1100 nm. The second sensor unit 400 may also be implemented as a single sensor. The second sensor unit 400 may be configured to detect light of a wide band wavelength. The second sensor unit 400 may be configured to detect light with a wavelength of 350 nm to 1100 nm.

The third mirror 140 may be disposed between the first mirror 110 and the first sensor unit 300. The first mirror 110 may be disposed inclined at 45 degrees with respect to the horizontal plane. The third mirror 140 may be disposed inclined in a direction of -45 degrees with respect to the horizontal plane. The first sensor unit 300 may be configured to receive the third transmitted light that has transmitted through the third mirror 140 and monitor the output power of the laser beam. In this regard, the third transmitted light, in which the light emitted from the light source 101 passes through the first mirror 110 and the third mirror 140, may be received by the first sensor unit 300.

The galvano mirror 120 may be implemented with one or more mirrors so that the path of emitted or transmitted light is changed step by step (gradually). The galvano mirror 120 may be configured to include a first galvano mirror 121 and a second galvano mirror 122.

The first galvano mirror 121 may be disposed in an area on the other side of the first mirror 110. The second mirror 130 may be disposed on one side of the first mirror 110. The first mirror 110 may be disposed between the first galvano mirror 121 and the second mirror 130. The first galvano mirror 121 may be configured to form first refracted light in which the first reflected light reflected from the first mirror 110 is refracted by a predetermined angle.

The second galvano mirror 122 may be disposed in an area on the other side of the first mirror 110. The second galvano mirror 122 may be disposed in a lower area on the other side of the first galvano mirror 121. A first galvano mirror 121 may be disposed between the first mirror 110 and the second galvano mirror 122. The second galvano mirror 122 may be configured so that the first refracted light refracted by the first galvano mirror 121 is refracted at a predetermined angle to form second refracted light in the downward direction.

The second sensor unit 400 may be configured to receive the third reflected light reflected from the third mirror 140 and monitor the reflected power of the laser beam.

Meanwhile, the laser welding monitoring system according to the present specification may be configured to control the operations of the above-described components. In this regard, FIG. 3 is a block diagram showing each configuration of the laser welding monitoring system of FIG. 1.

Referring to Figure 3, the laser welding monitoring system may be configured to include a work piece 10, a light source 101, a first mirror 110, and a galvano mirror 120. The laser welding monitoring system includes a control unit 180. ) may be configured to further include. The control unit 180 may be configured to detect welding abnormalities including gaps, focus changes, foreign matter, and folding phenomena based on the reflected power of the reflected light reflected from the work piece 10. there is.

Referring to FIG. 3, the laser welding monitoring system may be configured to selectively detect abnormal welding states of two or more work pieces. In this regard, the laser welding monitoring system may be configured to further include lenses 171 and 171b and glasses 172 and 172b.

The lenses 171 and 171b may be implemented as scanning lenses such as F-theta lenses. The lenses 171 and 171b may be configured to detect the surface shape, shape, and surface roughness of the work pieces 10 and 10b for each sub-area. The glasses 172 and 172b may be configured to cover the lenses 171 and 171b to protect the glasses 172 and 172b.

The control unit 180 may include a beam switch 181. The beam switch 181 may be configured to detect welding abnormalities for the first work piece 10 or the second work piece 10b by selecting any one of the first system 100a and the second system 100b. there is.

Collimators 102 and 102b may be configured to propagate incident light in parallel. The first collimator 102 may be disposed on the first path so that light from the light source 101 is applied to the first system 100a. The second collimator 102b may be disposed on the second path so that light from the light source 101 is applied to the second system 100b.

The first system 100a, which includes the first mirror 110, the galvano mirror 120, the lens 171, and the glass 172, is used to detect welding abnormalities in the work piece 10. A first scan head can be configured to scan for each area. The second system 100b, which includes the first mirror 110b, the galvano mirror 120b, the lens 171b, and the glass 172b, is used to detect welding abnormalities in the work piece 10b. A second scan head can be configured to scan for each area.

In the first system 100a, a beam monitoring unit 130 and a first sensor unit 300 may be disposed between the first mirror 110 and the galvano mirror 120. In the second system 100b, a beam monitoring unit 130b and a first sensor unit 300 may be disposed between the first mirror 110b and the galvano mirror 120b. The first transmitted light passing through the first mirrors 110 and 110b is transmitted to the beam monitoring units 130 and 130b and the first sensor units 300 and 300b. The first reflected light reflected from the first mirrors 110 and 110b is transmitted to the galvano mirrors 120 and 120b.

The reflected light reflected from the work piece 10 in the first system 100a may be transmitted to the second sensor unit 400. The reflected light reflected from the work piece 10b in the second system 100b may be transmitted to the second sensor unit 400b. The reflected light reflected from the work pieces 10 and 10b may pass through the galvano mirrors 120 and 120b and the first mirrors 110 and 110b and be transmitted to the second sensor units 400 and 400b.

1 to 3, the control unit 180 detects a welding abnormality based on the difference between the output power monitored by the first sensor unit 300 and the reflected power monitored by the second sensor unit 400. You can. Welding abnormalities may include incorrect laser beam emission, abnormal position emission, and jig joint defects.

The control unit 180 may set the image of the laser beam measured from the welded product in a normal state as the reference image. The control unit 180 may be configured to compare the image of the laser beam measured from the work piece with the reference image, monitor the quality of the laser beam, and detect contamination or damage to the optical system.

The control unit 180 may be configured to acquire time series data of reflected light measured from a welded product in a normal state. The control unit 180 may be configured to perform statistical and artificial intelligence-based learning using time series data of reflected light, and set a threshold value associated with the normal range based on the results of the learning. The control unit 180 may be configured to determine whether there is a welding abnormality in the work piece 10 based on a threshold value.

Specifically, beam quality monitoring may be performed in the beam monitoring unit 200. In this regard, if contamination/damage of the optical system occurs during the path from the optical fiber to the beam image camera, the laser beam cannot maintain its normal beam shape. Therefore, the normal shape of the laser beam can be set as the reference image. In this regard, the normal beam shape may differ depending on the mode of the laser.

Meanwhile, the image of the beam measured during the process of producing a normal welded product may be set as the reference image. Meanwhile, an algorithm that can detect changes in the shape of the beam can be established under the assumption that the shape of the beam changes when contamination/damage occurs. Regarding detecting changes in the shape of the beam, the total energy, shape, diameter, center position, etc. of the beam image may be considered. The results of the beam image measured according to each algorithm are compared with the reference image, and if the threshold value is exceeded, it can be judged/detected as a welding abnormality.

Real-time monitoring of the emission power of the laser may be performed in the first sensor unit 300 to which the laser beam is input. In this regard, since the influence of reflected light in the LBAD system is minimal, real-time monitoring of the output power of the laser can be performed. It may be difficult to directly distinguish welding abnormalities such as gaps, focus changes, foreign substances/folds, etc. using only the emitted light. Accordingly, additional abnormalities related to erroneous emission, abnormal position emission, coupling between jigs, etc. may be detected due to the difference between the measured signals of the amount of emitted light and the amount of incident light.

Measurement of back reflection may be performed in the second sensor unit 400. When abnormal phenomena such as power, gap, focus change, foreign matter/folding, etc. occur during welding, the post-radiated beam shows a pattern or characteristic that is different from the normal beam pattern. Accordingly, after acquiring light intensity time series data in a steady state, a normal range can be set after learning through statistical and AI-based methodology using the data. When an abnormality occurs, it may show patterns/features that are different from normal time series data. Therefore, other pattern characteristics are quantified through an algorithm to set a threshold, and if it exceeds the set threshold, it can be judged/detected as an abnormality in the welding area.

Meanwhile, the laser welding monitoring system that detects welding abnormalities in the plurality of work pieces 10 and 10b of FIG. 3 may be configured to detect welding abnormalities for each area of one work piece. In this regard, the first system 100a may be configured to detect a welding abnormality in the first area of the work piece 10. The second system 100b may be configured to detect a welding abnormality in the second area of the work piece 10.

Meanwhile, the laser welding monitoring system of FIG. 3 can simultaneously detect welding abnormalities for a plurality of work pieces 10 and 10b through the first and second systems 100a and 100b. Alternatively, the laser welding monitoring system of FIG. 3 may simultaneously detect welding abnormalities in a plurality of areas of one work piece through the first and second systems 100a and 100b. Accordingly, the laser welding monitoring system can quickly and accurately detect welding abnormalities for a plurality of work pieces or a single work piece of a certain size or more.

Meanwhile, the laser welding monitoring system according to the present specification can detect an abnormal state of the welded portion by measuring the post-radiation beam using an input beam with dynamically configured pulses for each time section. In this regard, FIG. 4 shows an embodiment of detecting an abnormal state of a welded portion by measuring a post-radiation beam using an input beam having pulses dynamically configured for each time section.

Figure 4(a) shows the input beam corresponding to the emitted light in a laser beam anomaly detection (LBAD) system by time section. The input beam can be obtained by measuring the bear beam after passing through the first mirror, which is a high-resolution (HR) mirror. The input beam can be considered a signal of the emitted light itself, as the influence of reflected light can be ignored below a certain level.

Figure 4(b) shows the back reflection beam by time section in the LBAD system. After the emitted light and the reflected light from the weld are combined, the radiation beam can be measured as shown in FIG. 4(b). In this regard, in the LBAD system, the phenomenon at the weld zone during welding is reflected in the reflected light, so that the after-radiation beam can be measured as shown in FIG. 4(b). Therefore, the present invention enables real-time confirmation of abnormalities during welding by checking laser power in real time.

In the LBAD system of FIG. 4, welding abnormalities can be detected using emitted light emitted from a laser light source and transmitted light and reflected light received from the first and second sensor units corresponding to the light quantity sensor. In an LBAD system, the data characteristics of a light sensor can be expressed in terms of an input beam and a post-emission beam.

1 to 4, the control unit 180 may be configured to apply first pulses having a first voltage to the work piece 10 in a first time period to monitor the first reflected voltage associated with the reflected power. there is. The control unit 180 may be configured to monitor the second reflected voltage in a second time period following the first time period. Specifically, the control unit 180 may be configured to monitor the second reflected voltage associated with the reflected power by applying second pulses having a second voltage greater than the first voltage to the work piece 10 in a second time period. . The control unit 180 may detect a welding abnormality of the work piece 10 based on the first reflection voltage and the second reflection voltage.

Meanwhile, the laser welding monitoring system according to the present specification may be configured to detect the power value of the post-radiation beam while changing the power value of the input beam within a time interval. In this regard, Figure 5 shows the results of detecting the power value of the post-radiation beam while changing the power value of the input beam within a time period in the laser welding monitoring system according to the present specification.

Figure 5(a) shows input beams corresponding to emitted light with different power values in each time section in a laser beam abnormality detection (LBAD) system. The input beam can be obtained by measuring the bear beam after passing through the first mirror, which is a high-resolution (HR) mirror. The power value of the input beam can be changed to have values of 50W, 100W, 150W, 200W, 250W, and 300W within a time period. Meanwhile, through a dummy power test, the power value can be changed within a predetermined range around the reference value even within a single time period.

Figure 5(b) shows the back reflection beam by time section after different power values in the LBAD system. After the emitted light and the reflected light from the weld are combined, the radiation beam can be measured as shown in FIG. 5(b). In this regard, in the LBAD system, the phenomenon at the weld zone during welding is reflected in the reflected light, so that the after-radiation beam can be measured as shown in FIG. 5(b). Therefore, the present invention enables real-time confirmation of abnormalities during welding by checking laser power in real time.

Referring to FIG. 5, as the power value of the input beam changes to a value of 50W, 100W, 150W, 200W, 250W, and 300W, the post-radiation beam may also change within a predetermined range based on the corresponding value. Accordingly, when the power value of the input beam changes, the power value of the post-radiation beam may also change linearly according to the power value of the input beam. Additionally, if the power value of the input beam varies within a predetermined range due to inaccuracy of the laser light source itself and system error, the range of variation in the power value of the post-radiation beam may be limited to within a specific error range. Accordingly, it can be confirmed that a linear sensor response occurs according to the laser output during the dummy power test in FIG. 5.

Meanwhile, the laser welding monitoring system according to the present specification may provide a specific UI screen displayed on the display of the control device to check the beam image, laser input beam, and post-radiation beam. In this regard, Figure 6 shows a specific UI screen displayed on the display of the control device to allow viewing the beam image, laser input beam and post-radiation beam in an embodiment.

Referring to FIG. 6, beam images may be displayed in the first area of the display. A laser input beam as shown in FIG. 4(a) or FIG. 5(a) may be displayed in the second area of the display. Additionally, a back reflection beam as shown in FIG. 4(b) or FIG. 5(b) may be displayed in the third area of the display.

Therefore, the laser beam anomaly detection (LABD) system according to the present invention can be implemented with integrated operation software and a beam monitoring dedicated algorithm. In addition, operation/control/real-time chart views and images of the LABD system can be provided through integrated operation software. Meanwhile, it is possible to set and apply algorithms to the time series and image data of the LABD system through integrated operation software. In addition, through the integrated operation software, it is possible to query raw data, check algorithm processing results, and search and view result trends.

In the above, the laser welding monitoring system according to the present specification has been described. The technical effects of the laser welding monitoring system according to the present specification can be summarized as follows.

According to at least one of the embodiments of the present invention, a system for detecting welding abnormalities using a laser beam can be provided.

According to at least one of the embodiments of the present invention, a laser welding monitoring system that monitors by including emitted light in addition to the existing welding monitoring system using only reflected light can be provided.

Existing laser welding monitoring systems that use only reflected light can only detect abnormalities during welding, but according to at least one embodiment of the present invention, not only abnormal phenomena during welding but also whether the abnormal phenomenon is actually a problem of deterioration of the quality of the welding beam is a problem. It is possible to accurately distinguish whether an abnormality occurred during welding.

According to at least one of the embodiments of the present invention, it is possible to solve the problem that it takes a lot of money and time to improve welding quality because it is difficult to determine the exact cause of the problem.

According to at least one of the embodiments of the present invention, laser welding quality control and improvement can be effectively performed using this laser welding monitoring system using both emitted and reflected light.

According to at least one of the embodiments of the present invention, laser welding quality control and improvement can be effectively performed using this laser welding monitoring system using both emitted and reflected light.

According to at least one of the embodiments of the present invention, contamination, damage, etc., which are factors that can affect beam quality, can be accurately measured by measuring the 2D image, shape, diameter, and center position of the beam in real time using emitted light. there is.

According to at least one of the embodiments of the present invention, abnormal phenomena occurring during laser welding can be systematically managed using a LBAD (Laser Beam Anomaly Detection) system that uses both emitted and reflected light, contributing to improving product competitiveness. You can.

The detailed description of the present invention described above should not be construed as restrictive in any respect and should be considered illustrative. The scope of the present invention should be determined by reasonable interpretation of the appended claims, and all changes within the equivalent scope of the present invention are included in the scope of the present invention.

Claims (12)

work piece;
a scanner configured to move in at least one axis direction to radiate a laser beam toward the work piece;
A beam monitoring unit configured to monitor the quality of a laser beam using emitted light from a light source and detect contamination or damage to the optical system;
a first sensor unit configured to monitor output power of the laser beam using the emitted light; and
A second sensor unit configured to monitor welding abnormalities of the work piece using reflected light reflected from the work piece,
The beam monitoring unit and the first sensor unit are provided in a first structure coupled to a lower end portion of the scanner,
The second sensor unit is provided in a second structure coupled to one side area of the scanner. According to claim 1,
The scanner is,
an optical fiber light source disposed in an upper area of the scanner and configured to generate the laser beam so that the emitted light travels in a downward direction;
a first mirror configured to separate the emitted light into first reflected light reflected in a horizontal direction and first transmitted light transmitted in a downward direction; and
A galvano mirror configured to change the direction of travel of the first reflected light,
The light passing through the galvano mirror is reflected at a welding point of the work piece and passes through the galvano mirror to form a second reflected light,
The second reflected light is configured to pass through the first mirror. According to clause 2,
The second structure is,
a second mirror provided inside the CCD camera, which is the second structure, and disposed between the first mirror and the first sensor unit; and
A second sensor unit disposed at one side of the CCD camera and configured to monitor welding abnormalities of the work piece using the second reflected light passing through the first mirror and the second mirror,
The second sensor unit is provided in a post-radiation acquisition unit of the second structure. According to clause 3,
The first structure is,
a third mirror configured to separate the first transmitted light into a third reflected light reflected in a horizontal direction and a third transmitted light transmitted in a downward direction;
The beam monitoring unit coupled to one side area of the first structure and configured to monitor the quality of the laser beam using the third reflected light reflected from the third mirror and detect contamination or damage to the optical system; and
comprising a first sensor unit coupled to a lower portion of the first structure and configured to monitor output power of the laser beam;
The first sensor unit is provided in the laser input beam acquisition unit of the first structure. According to paragraph 4,
The beam monitoring unit,
Detect the two-dimensional image and distribution of the laser beam, measure and store the shape of the laser beam,
Check the diameter and beam center position of the laser beam,
A laser welding monitoring system that detects contamination or damage to the optical system by detecting factors that affect the quality of the laser beam. According to paragraph 4,
The first sensor unit and the second sensor unit are configured to detect light with a wavelength of 350 nm to 1100 nm. According to clause 6,
The third mirror is disposed between the first mirror and the first sensor unit,
The first mirror is disposed inclined in a direction of -45 degrees with respect to the horizontal plane, and the third mirror is disposed in a form inclined in a direction of -45 degrees with respect to the horizontal plane,
The first sensor unit monitors the output power of the laser beam by receiving the third transmitted light that has transmitted through the third mirror. According to paragraph 2,
The galvano mirror is,
a first galvano mirror disposed on the other side of the first mirror and configured to form first refracted light in which the first reflected light reflected from the first mirror is refracted by a predetermined angle; and
A laser welding monitoring system comprising a second galvano mirror disposed in a lower area on the other side of the first galvano mirror and configured to form the first refracted light into second refracted light in a downward direction. According to clause 4,
The second sensor unit receives the third reflected light reflected from the third mirror and monitors the reflected power of the laser beam,
It further includes a control unit configured to detect the welding abnormalities including gaps, focus changes, foreign matter, and folding phenomena based on the reflected power,
The control unit,
Detecting a welding abnormality based on a difference between the output power monitored by the first sensor unit and the reflected power monitored by the second sensor unit,
The laser welding monitoring system wherein the welding abnormality includes erroneous emission of the laser beam, emission at an abnormal position, and defective jig coupling. According to clause 9,
The control unit,
Set the image of the laser beam measured on the welded product in a normal state as the reference image,
A laser welding monitoring system that compares the image of the laser beam measured from the work piece with the reference image to monitor the quality of the laser beam and detect contamination or damage to the optical system. According to clause 9,
The control unit,
Obtain time series data of reflected light measured from the welded product in a steady state,
Perform statistical and artificial intelligence-based learning using the time series data of the reflected light, and set a threshold associated with a normal range based on the results of the learning,
A laser welding monitoring system that determines whether there is a welding abnormality in the workpiece based on the threshold value. According to clause 9,
The control unit,
Monitoring a first reflected voltage associated with the reflected power by applying first pulses having a first voltage to the work piece in a first time interval;
monitoring a second reflected voltage associated with the reflected power by applying second pulses having a second voltage greater than the first voltage to the work piece in a second time interval subsequent to the first time interval;
A laser welding monitoring system that detects a welding abnormality of the work piece based on the first reflected voltage and the second reflected voltage.

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