Four-way line laser welding head and welding system

Abstract

The invention belongs to the field of laser welding detection, and discloses a four-way line laser welding head for real-time detection of laser welding and a welding system. The welding head comprises a laser welding head body and four linear laser sensor modules arranged on the four faces of a shell of a square base of the laser welding head body respectively. In each line laser sensor module, a line laser and a line laser reflector in the line laser sensor module are coplanar and are both arranged at the back of the board-level camera, an imaging lens is arranged in front of the board-level camera, and the reflection direction of the line laser reflector and the imaging lens both face a view field area. Line lasers projected by the four line laser reflectors form a closed rectangular area with a laser welding point as the center, and meanwhile, the imaging lens can collect images of the respective line lasers projected to the surface of a welding seam. Therefore, welding seam tracking and welding quality detection are simultaneously carried out through the four sensors, and the welding seams on the two sides of the corner are identified and tracked by using a multi-direction sensor module.

Description

Technical Field

[0001] The present invention belongs to the technical field related to laser welding, and more specifically, relates to a four-directional line laser welding head and a welding system. Background Art

[0002] The output value created by welding technology in the manufacturing industry accounts for a relatively large proportion. Currently, laser welding uses high-energy laser as the welding heat source, and melts and welds workpieces with a high-energy laser beam. It has the advantages of deep penetration, high speed, small deformation, low requirements for the welding environment, high power density, not affected by magnetic fields, not limited to conductive materials, no need for a vacuum working condition, and no X-rays generated during the welding process. It is widely used in the field of high-precision welding.

[0003] Currently, laser welding technology is tending towards automation and intelligence. The real-time requirements for weld seam recognition, tracking, and welding quality detection are continuously increasing. Correspondingly, the requirements for laser welding sensors are also continuously increasing. Existing welding vision sensors are mainly divided into passive vision sensors and active vision sensors. Among them, the active vision sensor with a laser as the light source often has higher anti-interference ability and stability in the application of high-power laser welding.

[0004] Most laser sensors identify weld seams in a teaching or scanning manner to guide laser welding. In this process, it is necessary to manually teach the position of the weld seam or completely scan all weld seams before welding, which is not conducive to the automation and real-time requirements of laser welding. Although some laser sensors can achieve real-time tracking of weld seams, most of them can only be applied in the two-dimensional laser welding process. And currently, most laser welding sensors with the functions of weld seam tracking and welding quality detection can only achieve one function at the same time. If you want to achieve the effects of weld seam tracking and welding quality detection in a single welding process, multiple sensors need to be installed on the laser welding head, which increases the overall volume of the welding system and reduces the flexibility of the system.

[0005] The laser welding head is generally installed on the robot arm. For a general six-axis robot, the robot posture needs to be changed according to the welding situation at the corner. When facing complex three-dimensional weld seams, especially at the corner of the weld seam, due to the distance between the installation positions of the welding laser head and the laser sensor, the weld seam recognition always precedes the completion of welding. When the weld seam recognition at the corner is completed and welding continues, it is necessary to drive the sensor to continue running along the recognized weld seam trajectory. At this time, since the robot needs to maintain the welding posture, the indicating laser of the sensor will deviate from the weld seam and cannot continue to track the weld seam on the other side of the weld seam corner. The optimal posture of the robot required for welding and the optimal posture of the robot for the sensor to recognize the weld seam will conflict at the corner. If the weld seam is to be continuously tracked, the welding robot posture can only be changed so that the sensor posture can perform weld seam recognition and make the indicating laser line return to the weld seam again. However, the change in the welding robot posture will change the welding effect and quality, and will also affect the continuity of the welding process, ultimately resulting in a decrease in the recognition accuracy at the weld seam corner.

[0006] In order to meet the requirements of automation and intelligence in the laser welding process, it is necessary to design a structure that can realize the real-time tracking function of three-dimensional weld seams, solve the contradiction between the welding posture and the sensing posture, and realize the functions of weld seam tracking and welding quality detection. Summary of the Invention

[0007] Aiming at the above defects or improvement requirements of the prior art, the present invention provides a four-way line laser welding head and a welding system. The purpose is to simultaneously perform weld seam tracking and welding quality detection through multiple miniaturized line laser sensor modules, and use multi-directional line laser sensor modules to identify and track the weld seams on both sides of the corner, thereby solving the technical problem that it is difficult for existing welding robots to achieve real-time detection and tracking of three-dimensional weld seams and weld seam quality detection.

[0008] To achieve the above object, according to the first aspect of the present invention, a four-way line laser welding head is provided, including four line laser sensor modules and a laser welding head; the four line laser sensor modules are respectively arranged on the four sides of the square base housing of the laser welding head;

[0009] Each line laser sensor module includes a line laser, a line laser mirror, an imaging lens, and a board-level camera; in each line laser sensor module, the line laser and the line laser mirror are coplanar and are both arranged on the back of the board-level camera, the imaging lens is arranged in front of the board-level camera, and the reflection direction of the line laser mirror and the imaging lens both face the field of view area, so that the line lasers projected by the four line laser mirrors form a closed rectangular area centered on the laser welding point on the welding surface, and at the same time, the imaging lens can collect the images of the line lasers projected onto the weld seam surface of their respective line lasers.

[0010] Preferably, in the present invention, the line laser wavelength in each of the line laser sensor modules is 400 - 650 nm, and the line laser wavelengths selected in the four line laser sensor modules are different from each other.

[0011] Preferably, in the present invention, the board-level camera includes a camera photosensitive chip; the camera photosensitive chip is arranged parallel to the line laser generated by the line laser.

[0012] Preferably, in each of the line laser sensor modules (1), the positional relationship between the line laser, the line laser mirror, the line laser generated by the line laser, the imaging lens, the camera photosensitive chip, and the surface of the welding seam generated by welding the laser welding head all satisfies the following formula:

[0013]

[0014] l1 tanα = l2 tanβ;

[0015]

[0016] Wherein, l1 is the distance from the surface of the welding seam to the center of the imaging lens, l2 is the distance from the center of the imaging lens to the center of the camera photosensitive chip, f is the focal length of the imaging lens, α is the angle between the line laser and the surface of the welding seam, β is the angle between the camera photosensitive chip and the imaging lens, and γ is the angle between the normal plane of the line laser mirror and the line laser generated by the line laser.

[0017] Preferably, in the present invention, the imaging lens is arranged in the imaging lens seat through internal threads.

[0018] Preferably, in the present invention, the centers of the imaging lens and the camera photosensitive chip are located on the same straight line.

[0019] Preferably, in the present invention, the line laser sensor module further includes a narrow-band filter, the narrow-band filter is arranged between the imaging lens and the camera photosensitive chip, and the center wavelength of the narrow-band filter is equal to the center wavelength of the line laser of the line laser sensor module.

[0020] Preferably, in the present invention, the line laser and the line laser mirror are arranged on the back of the board-level camera through the laser support seat, and the laser support seat is parallel to the line laser generated by the line laser; the laser support seat is fixed on the back of the board-level camera through the mounting screw holes of the line laser support seat, and the line laser is fixed on the laser support seat through the fixing screw holes of the line laser.

[0021] Preferably, the line laser sensor module is arranged on four sides of the four-sided base housing of the laser welding head through a sensor connection board, and the sensor connection board is fixed on four sides of the four-sided base housing of the laser welding head through sensor module connection screw holes.

[0022] According to another aspect of the present invention, the present invention also provides a four-way line laser welding system, including a four-way line laser welding head as described in one aspect of the present invention, a welding laser access optical fiber, an image processing system and a control system; the welding laser access optical fiber is electrically connected to the four-way line laser welding head for introducing welding laser into the four-way line laser welding head; the image processing system is electrically connected to the camera circuit board of the four-way line laser welding head for performing image processing on the collected image information; the control system is connected to the four-way line laser welding head for controlling the welding position and posture of the four-way line laser welding head.

[0023] Generally speaking, compared with the prior art by the above technical solutions conceived by the present invention, the following technical advantages are mainly possessed:

[0024] (1) For the whole process of weld detection, by optimizing the traditional sensor optical path system, the present invention designs a miniaturized line laser vision sensor module, and installs multiple sensor modules in four directions of the laser welding head. The multiple generated line lasers form a closed area centered on the welding laser, ensuring that there is always a sensor module that can identify the weld during the whole welding process. Therefore, based on the image information collected by the four laser vision sensor modules, the functions of weld tracking and welding quality detection can be simultaneously realized during a single welding process.

[0025] (2) Especially for the situation where the recognition accuracy of the sensor at the corner weld is insufficient, the sensor of the present invention can combine the sensor module on the welding advancing side in the four-way line laser welding head device to determine the welding position information, improve the recognition accuracy of the sensor system at the corner weld, and ensure the continuity of the welding process.

[0026] (3) Preferably, four sensor modules are installed in four directions of the laser welding head, and the line lasers in each sensor module have different wavelengths as indicating lasers to distinguish the four directions of the laser welding head's advancement.

[0027] (4) Preferably, the optical structure of the line laser sensor module satisfies the imaging conditions of the optical system and the Scheimpflug conditions (such as equations (1), (2), and (3) in the present invention), so that the laser line is completely located within the focal plane, ensuring that the line laser sensor module has a large depth of field while obtaining clear images.

[0028] (5) Preferably, the narrowband filter in the present invention is installed at the bottom of the imaging lens holder through a filter retaining ring, and its corresponding narrowband wavelength corresponds to the wavelength of the line laser of the sensor module, so as to filter out the stray light reflected when the high-intensity welding laser acts on the surface of the welded part, and prevent the corresponding camera photosensitive chip from collecting the line laser image information of other sensor modules, reducing the interference between the image information collected by the sensor modules.

[0029] In summary, a four-way line laser welding head provided by the present invention simultaneously performs weld seam tracking and welding quality detection functions through multiple miniaturized line laser sensor modules, and uses multi-directional line laser sensor modules to identify and track the weld seams on both sides of the corner for corner welds, thereby solving the technical problems that existing welding robots are difficult to achieve real-time detection and tracking of three-dimensional weld seams and weld quality detection. Brief Description of the Drawings

[0030] Figure 1 Schematic structural diagram of the sensor module according to an example of the present invention;

[0031] Figure 2 Top view of the structural diagram of the sensor module according to an example of the present invention;

[0032] Figure 3 is Figure 2 Cross-sectional view taken along the A-A direction in

[0033] Figure 4 Schematic structural diagram of the four-way line laser welding head according to an example of the present invention;

[0034] Figure 5 Schematic optical structure diagram of the line laser sensor module according to an example of the present invention;

[0035] Figure 6 Schematic diagram of the laser line of the non-corner weld according to an example of the present invention;

[0036] Figure 7 Schematic diagram of the laser line of the corner weld according to an example of the present invention.

[0037] In all the drawings, the same reference numerals are used to represent the same structures, where:

[0038] In the accompanying drawings: 1 - line laser sensor module, 2 - line laser, 3 - fixing screw hole for line laser, 4 - line laser mirror, 5 - line laser, 6 - imaging lens, 7 - imaging lens holder, 8 - support base for line laser, 9 - mounting screw hole for support base of line laser, 10 - camera circuit board, 11 - sensor connection plate, 12 - sensor module connection screw hole, 13 - filter retaining ring, 14 - narrowband filter, 15 - camera photosensitive chip, 16 - laser welding head, 17 - welding laser, 18 - optical fiber for accessing welding laser, 19 - workpiece to be welded, 20 - welding seam, 21 - laser spot of forward sensor, 22 - laser spot of backward sensor, 23 - laser spot of lateral sensor. Detailed implementation manners

[0039] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0040] In order to solve the above problems, the present invention provides a laser welding head and a welding system applicable to the whole process of laser welding, which have the functions of weld seam tracking and welding quality detection, and can especially effectively improve the weld seam recognition accuracy at the corner weld seam.

[0041] In the first aspect of the present invention, as Figure 4 shown, a four-directional line laser welding head is provided, which includes four miniaturized line laser sensor modules 1 and a laser welding head 16;

[0042] In each line laser sensor module, the line laser sensor module 1 is based on the triangulation principle and includes a line laser 2, a line laser mirror 4, an imaging lens 6 and a board-level camera; both the line laser 2 and the line laser mirror 4 are arranged on the back of the board-level camera; the line laser 2 and the line laser mirror 4 are coplanar to receive the laser beam from the line laser 2 and reflect it; the imaging lens 6 is arranged in front of the board-level camera, and the reflection direction of the imaging lens 6 and the line laser mirror 4 both face the field of view area;

[0043] The four miniaturized line laser sensor modules 1 are respectively arranged on the four sides of the square base housing of the laser welding head 16, and the reflection direction of the line laser mirror 4 in the same line laser sensor module 1 is towards the welding field of view area of the laser welding head (i.e., near the center of the welding laser 17), so that the line laser 5 emitted by the line laser 2 in the four miniaturized line laser sensor modules 1 is projected near the center of the welding laser 17 through the line laser mirror 4, and a closed rectangular area is formed on the same welding plane with the laser welding point as the center. At the same time, the imaging lens 6 in the line laser sensor module 1 collects the images of the line laser 5 belonging to each module projected onto the weld surface.

[0044] Furthermore, the line laser 5 emitted by the line laser 2 in the four miniaturized line laser sensor modules 1 is projected near the center of the welding laser 17 through the line laser mirror 4. At this time, the distance range where the four line lasers 5 are projected near the center of the welding laser 17 is that the distance between the laser spots generated by the four line lasers 5 and the center point of the welding laser 17 is from one-half to all of the field of view size of the line laser sensor. At the same time, the field of view area or field of view size of the present invention is generally related to the structural arrangement of the sensor and is obtained through measurement.

[0045] In actual use, based on the high-uniformity and narrow-width line laser generated by the above line laser sensor module, due to different structural characteristics in the weld area, when the line laser irradiates the weld surface, the reflected light beams of the line laser for different weld structures will have different image information. The reflected light beams are imaged in the camera, and the image is transmitted to the corresponding image processing terminal to extract the position and shape information of the weld. By adopting the above optical system structure, the volume of the sensor module can be reduced, enabling multiple sensor modules to be installed on the laser welding head. For the non-corner weld process, the line laser of the line laser sensor module located in the positive direction of the welding travel irradiates the surface of the unwelded weld, and its weld image features are used for weld tracking. The line laser of the line laser sensor module located in the negative direction of the welding travel irradiates the surface of the welded weld, and its weld image features are used for weld quality inspection. For the corner weld process, when the welding laser beam approaches the weld corner, the line laser deviates from the weld. At this time, the line laser of the sensor module on the side in the positive direction of the welding travel is projected to the other side of the weld corner. After entering the weld corner area, the image information generated by the line laser of the side sensor module perpendicular to the travel direction on one side of the corner starts to include the information of the other side of the weld to ensure that the weld tracking continues after the image information of the line laser of the sensor module in the positive direction of the travel disappearing from the weld. Similarly, the line laser of the line laser sensor module located in the negative direction of the welding travel irradiates the surface of the welded weld, and its weld image features are used for weld quality inspection.

[0046] In some embodiments, four line laser sensor modules are mounted on the four sides of the square base housing of the laser welding head. The wavelength of the line laser in each line laser sensor module is 400 - 650 nm, and different wavelengths are selected as the indicating lasers respectively to distinguish the four directions of the laser welding head's movement. For example, the different wavelengths of the line lasers in the line laser sensor modules are 405 nm, 450 nm, 550 nm, and 650 nm respectively, which are used to indicate the four directions respectively.

[0047] In some embodiments, the board-level camera includes a camera circuit board 10 and a camera photosensitive chip 15 connected to the camera circuit board 10. The camera photosensitive chip 15 is disposed within the housing of the board-level camera and is parallel to the propagation direction of the line laser beam 5 generated by the line laser 2.

[0048] In some embodiments, as Figure 5 shown, the positional relationship between the line laser 2, the line laser mirror 4, the line laser 5, the imaging lens 6, and the surface of the welding seam 20 generated by the welding of the camera photosensitive chip 15 and the laser welding head 16 should satisfy the following formula:

[0049]

[0050] l1 tanα = l2 tanβ Equation (2);

[0051]

[0052] Wherein in the formula: l1 is the distance from the surface of the welding seam 20 to the center of the imaging lens 6, l2 is the distance from the center of the imaging lens 6 to the center of the camera photosensitive chip 15, f is the focal length of the imaging lens 6, α is the angle between the line laser 5 and the surface of the welding seam 20, β is the angle between the camera photosensitive chip 15 and the imaging lens 6, and γ is the angle between the normal plane of the line laser mirror 4 and the propagation direction of the line laser beam 5. The optical structure of the line laser sensor module satisfies the imaging conditions of the optical system and the Scheimpflug conditions (Equation (1), Equation (2), Equation (3)) so that the laser line is completely located within the focal plane, aiming to have a large depth of field while ensuring that the sensor module obtains a clear image.

[0053] The following provides an example through the specific selection of the above various structural relationships. The distance from the surface of the welding seam 20 to the center of the imaging lens 6 is 100.19 mm, the distance from the center of the imaging lens 6 to the center of the camera photosensitive chip 15 is 22.31 mm, the focal length of the imaging lens 6 is set to 25 mm, the angle between the line laser 5 and the surface of the welding seam 20 is 30°, the angle between the camera photosensitive chip 15 and the imaging lens 6 is 60°, and the angle between the normal plane of the line laser mirror 4 and the beam propagation direction of the line laser 5 is 45°. Thus, the line laser 5 emitted by the line laser 2 in the four miniaturized line laser sensor modules 1 can be projected near the center of the welding laser 17 through the line laser mirror 4 to form a closed rectangular area centered on the laser welding point. At the same time, the imaging lens 5 in the line laser sensor module 1 collects the images of the respective line laser 5 projected onto the weld surface.

[0054] Refer to Figure 1 、 Figure 3 and Figure 4 , and further optimize the details in the line laser sensor module 1. The example is as follows.

[0055] In some embodiments, in the four-way line laser welding head, the imaging lens 6 is installed into the imaging lens holder 7 through an internal thread, and the position is changed by rotating the imaging lens to obtain a clearer image. The imaging lens 6 and the camera photosensitive chip 15 form a certain angle, and the centers of the imaging lens 6 and the camera photosensitive chip 15 are located on the same straight line, so that the line laser image on the weld surface is imaged onto the camera photosensitive chip 15 through the imaging lens 6.

[0056] In some embodiments, the line laser sensor module 1 preferably includes a narrowband filter 14, which is arranged behind the imaging lens 6, between the imaging lens 6 and the camera photosensitive chip 15. Its corresponding narrowband wavelength corresponds to the wavelength of the line laser in the sensor module, that is, the central wavelength of the narrowband filter is equal to the central wavelength of the line laser of the line laser sensor module, so as to filter out the stray light reflected when the high-intensity welding laser acts on the surface of the welded part, and prevent the corresponding camera photosensitive chip from collecting the line laser image information of other sensor modules, reducing the interference between the image information collected by the sensor modules. Or, if the imaging lens 6 is installed into the imaging lens holder 7 through an internal thread, the narrowband filter 14 is installed at the bottom of the imaging lens holder 7 through the filter 13 retaining ring.

[0057] In some embodiments, in the four-directional line laser welding head, the line laser 2 and the line laser mirror 4 are arranged on the back of the board-level camera through the laser support base 8. The laser support base 8 is fixed to the back of the board-level camera through the mounting screw holes 9 of the line laser support base, and the line laser 2 is fixed to the laser support base 8 through the fixing screw holes of the line laser. The line laser 2 and the line laser 5 are arranged coplanarly, the beam propagation of the line laser 5 is parallel to the plane of the laser support base 8, and the center of the laser beam is collinear with the center of the line laser mirror 4.

[0058] In some embodiments, in the four-directional line laser welding head, the line laser sensor module 1 is arranged on the four sides of the four-sided base housing of the laser welding head 16 through the sensor connection board 11, and the sensor connection board 11 is fixed to the four sides of the four-sided base housing of the laser welding head 16 through the sensor module connection screw holes 12.

[0059] In another aspect of the present invention, the present invention also provides a four-directional line laser welding system, including the four-directional line laser welding head, the welding laser access optical fiber, the image processing system, and the control system provided in any of the above embodiments.

[0060] The welding laser access optical fiber is integrally electrically connected to the four-directional line laser welding head for introducing the welding laser into the welding head.

[0061] The image processing system is electrically connected to the camera circuit board in the four-directional line laser welding head for performing image processing on the collected image information, obtaining the weld position information for welding trajectory planning, and obtaining the welding shape information for welding quality detection.

[0062] The control system is integrally mechanically connected to the four-directional line laser welding head device for controlling the overall welding position and posture of the welding head.

[0063] Based on the above four-directional line laser welding head, when integrated into the four-directional line laser welding system, its methods in different welding requirements are different. Specifically as follows:

[0064] During the welding process of non-corner welds, the line laser of the sensor module located in the forward direction of the laser welding head travels irradiates the surface of the un-welded weld, and its weld image features will be used for weld tracking. Specifically, the weld surface image collected by the line laser sensor module contains the position coordinate information of the line laser. In the image processing terminal, the image coordinate information can be transformed into weld coordinate information through the corresponding coordinate transformation formula, and then the welding path can be planned. The line laser of the sensor module located in the reverse direction of travel irradiates the surface of the weld after welding, and its weld image features are used for weld quality detection. Specifically, the weld image information after welding collected by the line laser sensor module is modeled in the image processing terminal to restore the shape features of the weld after welding, and the welding quality is judged through the corresponding evaluation method.

[0065] During the welding process of the fillet weld, when the welding laser beam approaches the weld corner, the line laser deviates from the weld. At this time, since the welding of the weld on one side of the corner is not completed, it is impossible to change the attitude of the sensor by changing the attitude of the laser welding head, resulting in the loss of the weld tracking image and thus a decrease in the weld recognition accuracy. At this time, the line laser of the sensor module located on the side of the welding progress direction projects onto the other side of the weld corner. After entering the weld corner area, the lateral sensor module on the side perpendicular to the progress direction can collect the image information of the other side of the weld. After the image information is processed by the image processing terminal, after the line laser of the sensor module in the welding progress direction deviates from the weld and the image information disappears, it continues to guide the weld tracking.

[0066] It should be noted that when the four-way line laser welding head in the present invention faces different types of weld corners, the indication laser on the side of the welding progress direction will change differently. Through the image processing algorithm, the shape characteristics of the corner weld can be judged through this change, and then the weld path can be planned.

[0067] Specifically, the characteristics of the four-way line laser welding head will be described in detail below in combination with optional embodiments:

[0068] As Figure 1 is a schematic structural diagram of the miniaturized line laser sensor module 1 involved in the present invention. The line laser 2 is installed on the line laser support seat 8 through the line laser fixing screw hole 3. The line laser mirror 4 is installed on the line laser support seat 8 through the line laser fixing screw hole 3, and the position of the mirror of the line laser mirror 4; the imaging lens seat 7 and the line laser support seat 8 are connected through the line laser support seat mounting screw hole 9, and the camera circuit board 10 and the camera photosensitive chip 15 are fixed inside. And the imaging lens imaging 6 is set so that the relationship between it and the line laser 5 generated by the line laser 2 and the line laser mirror 4 satisfies the preferred relational expressions (such as Equation (1), Equation (2) and Equation (3)) in the above embodiments. Thus, the line laser 5 generated by the line laser 2 irradiates the weld surface after passing through the line laser mirror 4, and different image information will be generated according to the type, distance, and material of the weld. These image information are imaged by the reflected light beam through the imaging lens 6. The imaging lens 6 is installed in the imaging lens seat 7, and the image information collected by the camera is transmitted to the subsequent image processing and control module, and the weld characteristics are identified through the corresponding algorithm and the welding robot is controlled to move. By adopting the above optical system structure, the volume of the sensor module can be reduced, so that multiple sensor modules can be installed on the laser welding head.

[0069] As Figure 2 is a top view of the miniaturized line laser sensor module involved in the present invention, as Figure 3It is a sectional view in the A-A direction. The narrowband filter 14 corresponding to the laser wavelength is installed at the bottom of the imaging lens holder 7 through the filter pressing ring 13. Its corresponding narrowband wavelength corresponds to the line laser wavelength of the sensor module, and is used to filter out the stray light reflected when the high-intensity welding laser acts on the surface of the welded part. The imaging lens 6 is installed into the imaging lens holder 7 through internal threads, and the position of the imaging lens is changed by rotation to adjust the focal length to obtain a clearer image. The imaging lens 6 and the camera sensor chip 15 have an angle, aiming to enable the imaging lens to have a larger depth of field, so that the sensor module can obtain clear images in a larger range and increase the working distance of the sensor. The centers of the imaging lens 6 and the camera sensor chip 15 are located on the same straight line, so that the line laser image on the weld surface is imaged onto the camera sensor chip 15 through the imaging lens 6, and the image information is transmitted to the image processing terminal through the interface on the camera circuit board 10.

[0070] Such as Figure 4 It is a schematic diagram of the local structure of a four-way line laser welding system. Four miniaturized line laser sensor modules 1 are installed on the four sides of the laser welding head 16 through the sensor connection plate 11 via the sensor module connection screw holes 12. The four sensor modules are used to indicate the four directions during the welding process. The generated line laser 5 is centered on the welding laser 17, and the four laser lines adopt different wavelengths to number the four directions of the laser welding head and determine the direction of each laser line corresponding to the laser welding head. The welding laser 17 is connected to the laser welding head through the welding laser 18 accessing the optical fiber and performs welding under the control of the sensor information in the four directions and the image processing terminal.

[0071] Figure 6 It is a schematic diagram of the laser lines at the non-corner weld of the welded workpiece 19 in the four-way line laser welding system. The line laser 5 generated by the four miniaturized sensor modules 1 is projected onto the welding seam 20 of the welded workpiece 19, and the forward sensor laser spot 21, the backward sensor laser spot 22, and the lateral sensor laser spot 23 form a rectangular measurement area. During the welding process of the non-corner weld, if the welding is carried out in the direction of the arrow in the figure, the image information of the forward sensor laser spot 21 will be used for weld tracking, and the image information of the backward sensor laser spot 22 will be used for detecting the welding quality after welding. The same method is followed when the welding is carried out in other directions.

[0072] Figure 7It is a schematic diagram of the laser line of the four-way line laser sensor at the corner weld of the welded workpiece 19. As the welding progresses and the laser focus of the welding approaches the corner of the weld, the laser spot 21 of the forward sensor deviates from the weld. At this time, since the welding on one side of the corner has not been completed, it is impossible to change the attitude of the sensor by changing the attitude of the laser welding head, resulting in the loss of the weld tracking image and thus a decrease in the weld recognition accuracy. After adopting the four-way line laser sensing system described in the present invention, due to the existence of the laser spot 23 of the lateral sensor on the other side of the weld corner, the image information of the laser spot 23 of the lateral sensor gradually shows the information of the weld on the other side after entering the weld corner area. After the image information is processed by the image processing terminal, it can continue to guide the weld tracking after the image information of the laser spot 21 of the forward sensor disappears from the weld. The welding of the corner welds in other directions is also carried out in the same way to solve the problem of reduced recognition accuracy at the weld corners.

[0073] Obviously, those skilled in the art can make various modifications and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the present invention and its equivalent technologies, the present invention also intends to include these modifications and variations. The above-described embodiments are only preferred embodiments given to fully illustrate the present invention, and the scope of protection is not limited thereto. Equivalent substitutions or transformations made by those skilled in the art on the basis of the present invention are all within the scope of protection of the present invention.

Claims

1. A four-way line laser welding head, characterized in that: It comprises a laser welding head (16) and four line laser sensor modules (1), wherein the four line laser sensor modules (1) are respectively arranged on four sides of a square base shell of the laser welding head (16); Each of the line laser sensor modules (1) comprises a line laser (2), a line laser reflector (4), an imaging lens (6) and a board-level camera; in each of the line laser sensor modules (1), the line laser (2) and the line laser reflector (4) are coplanar and are both arranged on the back of the board-level camera, the imaging lens (6) is arranged in front of the board-level camera, and the reflection direction of the line laser reflector (4) and the imaging lens (6) are both facing the field of view area, so that the line lasers (5) projected by the four line laser reflectors (4) form a closed rectangular area on the welding surface with the laser welding point as the center, and at the same time, the imaging lens (6) can collect the images projected by the respective line lasers onto the weld surface.

2. The four-way linear laser welding head according to claim 1, characterized in that: The wavelength of the line laser in each of the line laser sensor modules (1) is 400-650 nm, and the wavelengths of the line lasers in the four line laser sensor modules (1) are selected differently.

3. The four-way linear laser welding head according to claim 1, characterized in that: The board-level camera comprises a camera photosensitive chip (15); the camera photosensitive chip (15) is arranged in parallel with the line laser (5) generated by the line laser (2).

4. The four-way linear laser welding head according to claim 3, characterized in that: In each of the line laser sensor modules (1), the positional relationship between the line laser (2), the line laser reflector (4), the line laser (5) generated by the line laser (2), the imaging lens (6), the camera photosensitive chip (15) and the surface of the welding seam (20) generated by welding with the laser welding head (16) all satisfies the following formula: l1 tanα=l2 tanβ; Wherein, l1 is the distance from the surface of the welding seam (20) to the center of the imaging lens (6), l2 is the distance from the center of the imaging lens (6) to the center of the camera photosensitive chip (15), f is the focal length of the imaging lens (6), α is the angle between the line laser (5) and the surface of the welding seam (20), β is the angle between the camera photosensitive chip (15) and the imaging lens (6), and γ is the angle between the normal plane of the line laser reflector (4) and the line laser (5) generated by the line laser (2).

5. The four-way linear laser welding head according to claim 1, characterized in that: The imaging lens (6) is arranged in the imaging lens seat (7) via an internal thread.

6. The four-way linear laser welding head according to claim 3, characterized in that: The center of the imaging lens (6) and the camera photosensitive chip (15) are located on the same straight line.

7. The four-way linear laser welding head according to claim 3, characterized in that: The line laser sensor module (1) further comprises a narrowband filter (14), wherein the narrowband filter (14) is arranged between the imaging lens (6) and the camera photosensitive chip (15), and the central wavelength of the narrowband filter (14) is equal to the central wavelength of the line laser of the line laser sensor module (1).

8. The four-directional linear laser welding head according to claim 1, characterized in that: The line laser (2) and the line laser reflector (4) are arranged on the back of the board-level camera via the laser support seat (8), and the laser support seat (8) is parallel to the line laser (5) generated by the line laser (2); the laser support seat (8) is fixed to the back of the board-level camera via the line laser support seat mounting screw hole (9), and the line laser (2) is fixed to the laser support seat (8) via the line laser fixing screw hole (9).

9. The four-directional linear laser welding head according to claim 1, characterized in that: The line laser sensor module (1) is arranged on the four sides of the square base shell of the laser welding head (16) through a sensor connecting plate (11), and the sensor connecting plate (11) is fixed to the four sides of the square base shell of the laser welding head (16) through sensor module connecting screw holes (12).

10. A four-directional line laser welding system, characterized in that: The invention comprises a four-directional line laser welding head, a welding laser access optical fiber, an image processing system and a control system as described in any one of claims 1 to 9; the welding laser access optical fiber is electrically connected to the four-directional line laser welding head for introducing the welding laser into the four-directional line laser welding head; the image processing system is electrically connected to a camera circuit board of the four-directional line laser welding head for performing image processing on the collected image information; The control system is connected to the four-directional line laser welding head and is used to control the welding position and posture of the four-directional line laser welding head.

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