Rectangular frame automatic welding seam tracking method based on multi-source control

Abstract

The invention discloses an automatic welding seam tracking method for a rectangular frame based on multi-source control. Linear lasers emitted by at least two linear laser emitters intersect at a welding seam on a welded piece; the position of the linear laser is recognized through a laser sensor installed at the end of the welding mechanical arm, and a welding head of the welding mechanical arm is guided to move towards the position of the linear laser; a welding head of the welding mechanical arm is guided to move to one end of linear laser through a cylindrical laser transmitter, temperature distribution of the surface of the welded piece is detected through an infrared temperature imager installed on the periphery of the welded piece or integrated on the end portion of the welding mechanical arm, and the welding head of the welding mechanical arm is guided to move from a high-temperature area to a low-temperature area; detection data of the laser sensor and the infrared temperature imager are received through the data processing and control module, a multi-element adjusting mechanism of linear laser guiding, projection spot ring calibration and temperature distribution correction is formed, and the welding device can be adapted to welding of different batches and different products without manual programming.

Description

Technical Field

[0001] This invention relates to the field of automatic welding technology, and more specifically to an automatic welding seam tracking method for rectangular frames based on multi-source control. Background Technology

[0002] In existing automated welding technology, before welding begins, a control program needs to be manually programmed on-site based on the welding trajectory. However, if the workpiece is misaligned due to large processing tolerances or deformation, the weld seam will shift, requiring manual intervention to adjust the program. This makes it difficult to adapt to welding small batches of products with many differences. If an image recognition sensor is used to detect the weld seam shift, welding needs to be paused for adjustment, affecting processing efficiency. Furthermore, it is limited by welding fumes and cannot cover all welding tasks. Summary of the Invention

[0003] Purpose of the invention: In order to overcome the shortcomings of the existing technology, the present invention provides an automatic welding seam tracking method for rectangular frames based on multi-source control. It can adapt to welding of different batches and different products without manual programming, accurately guide the welding path, monitor the weld seam status in real time, avoid pausing welding for adjustment, and ensure welding continuity and accuracy.

[0004] Technical solution: To achieve the above objectives, the present invention provides an automatic welding seam tracking method for rectangular frames based on multi-source control, comprising:

[0005] Construct a welding guide line, attach several linear laser emitters to the surface of the workpiece, and control and adjust the attitude of each linear laser emitter so that the linear lasers emitted by at least two linear laser emitters converge at the weld seam on the workpiece.

[0006] The welding head position is calibrated by identifying the location of the linear laser using a laser sensor mounted on the end of the welding robot arm, and guiding the welding head of the welding robot arm to move toward the location of the linear laser until the welding head of the welding robot arm is directly facing the linear laser.

[0007] The welding point position is calibrated so that the laser emitted by the cylindrical laser emitter mounted on the end of the welding robot arm forms a projection circle on the surface of the workpiece. The cylindrical laser emitter guides the welding head of the welding robot arm to move to one end of the linear laser, that is, the projection circle formed by the laser emitted by the cylindrical laser emitter is directly opposite one end of the linear laser. During welding, the intersection of the projection circle and the linear laser is the positive welding point, that is, the welding point that needs to be welded at this moment.

[0008] Temperature guidance is constructed by detecting the temperature distribution on the surface of the workpiece by an infrared temperature imager installed around the workpiece or integrated into the end of the welding robot arm, identifying high-temperature and low-temperature zones in the temperature distribution, and guiding the welding head of the welding robot arm to move from the high-temperature zone to the low-temperature zone.

[0009] A multi-dimensional adjustment mechanism is constructed. By receiving detection data from the laser sensor and infrared temperature imager through the data processing and control module integrated in the welding robot control system, a multi-dimensional adjustment mechanism is formed, which includes linear laser guidance, projection spot calibration, and temperature distribution correction. The data processing and control module controls the movement of the welding head of the welding robot based on the final output of the multi-dimensional adjustment mechanism.

[0010] Furthermore, constructing the welding guide wire includes:

[0011] Several linear laser emitters are installed on both sides of the weld along the length of the weld. Two linear laser emitters located on either side of the same point along the length of the weld are called a linear laser emitter group. The installation angle and height of each linear laser emitter are adjusted so that the linear lasers emitted by the two linear laser sensors in each group form an intersection point at any cross section of the corresponding weld, and the line connecting all intersection points coincides with the center line of the weld.

[0012] Furthermore, the frequency of each of the linear laser emitters is adjusted, and the linewidth of the linear laser emitted by each linear laser emitter is equal to the width of the weld.

[0013] Furthermore, the calibration of the welding head position includes:

[0014] During installation, the three-dimensional deviation data between the laser sensor and the welding head end is recorded in the data processing and control module;

[0015] A three-dimensional spatial coordinate system is established, and the three-dimensional deviation data between the laser sensor and the welding head end is substituted into the spatial coordinate system to calculate the coordinate information of the laser sensor in the spatial coordinate system.

[0016] The laser sensor collects the contour information of the linear laser emitted by the linear laser emitter in real time and transmits it to the data processing and control module. The data processing and control module can convert this contour information into three-dimensional coordinate data and calculate the three-dimensional coordinate data of the center line of the linear laser contour.

[0017] Furthermore, the method for establishing the three-dimensional spatial coordinate system includes:

[0018] Set the position of the welding head end as the origin of the three-dimensional spatial coordinate system;

[0019] Set the weld extension direction as the X-axis;

[0020] Set the axis of the welding head as the Z-axis;

[0021] Set the direction of the plane formed by the perpendicular X-axis and Z-axis as the Y-axis.

[0022] Furthermore, the data processing module calculates the deviation between the current welding head position and the linear laser position, that is, it calculates the deviation between the linear laser position and the origin on the X and Y axes in the spatial coordinate system. Based on the deviation calculation results, the posture of the welding robot arm is adjusted so that the welding head of the welding robot arm is directly facing the plane of the linear laser, that is, the Z axis of the spatial coordinate system is perpendicular to the plane formed by the X and Y axes, and the axis of the welding head of the welding robot arm is perpendicular to the center line of the linear laser profile.

[0023] Furthermore, the calibration welding point location includes:

[0024] Adjust the installation angle of the adjustable cylindrical laser emitter so that its laser projection direction is consistent with the welding direction of the welding head;

[0025] Adjust the power of the adjustable cylindrical laser emitter so that the diameter of the projected spot circle formed by the laser emitted by the cylindrical laser emitter on the workpiece is equal to the width of the weld, that is, the diameter of the projected spot circle is equal to the line width of the linear laser.

[0026] The laser sensor collects the contour information of the spot circle within the linear laser contour emitted by the cylindrical laser emitter in real time and transmits it to the data processing and control module. The data processing and control module can convert this contour information into three-dimensional coordinate data and calculate the three-dimensional coordinate data of the spot circle contour.

[0027] During the welding preparation stage, the laser emitted by the cylindrical laser emitter is projected onto one end of the linear laser, i.e., the three-dimensional coordinate data of the spot contour is the same as the three-dimensional coordinate data of one end of the linear laser contour.

[0028] Furthermore, during the welding process, the linear laser emitted by the linear laser emitter and the projection spot formed by the cylindrical laser emitter cooperate with each other. The data processing and control module forms laser guidance for the welding path of the welding head of the welding robot arm based on the detection results of the laser sensor, thereby guiding and controlling the welding head of the welding robot arm to gradually move from one end of the linear laser to the other end.

[0029] Furthermore, the construction temperature guidance includes:

[0030] The infrared temperature imager detects the temperature distribution of the workpiece in real time.

[0031] During the welding process, the weld seam of the workpiece is divided into welded points, positive weld points, and unwelded points along the welding direction. The welded points and unwelded points are located on both sides of the positive weld point, and the unwelded points are located in front of the welding direction. In the temperature distribution thermal image detected by the infrared temperature imager, the welded points, positive weld points, and unwelded points respectively form a residual temperature zone, a high temperature zone, and a low temperature zone, and the temperature of the residual temperature zone is higher than that of the low temperature zone. The infrared temperature imager transmits the detection results to the data processing and control module. The data processing and control module forms temperature guidance based on the distribution of the residual temperature zone, high temperature zone, and low temperature zone in the temperature distribution thermal image, and controls the welding head of the welding robot arm to move from the high temperature zone to the low temperature zone.

[0032] Beneficial Effects: Compared with the prior art, the automatic welding seam tracking method for rectangular frames based on multi-source control of the present invention has the following beneficial effects:

[0033] 1. When changing the type of workpiece to be welded, there is no need to manually re-program the welding trajectory. By constructing a guide line with a linear laser and calibrating with a laser sensor and a cylindrical laser, the welding head of the welding robot arm can be quickly aligned with the weld seam and can automatically track the weld seam. It is suitable for mass production and small-batch sample preparation, and can also handle situations where the workpiece is placed crookedly or has large differences.

[0034] 2. An infrared temperature imager is used to construct temperature guidance, which is combined with laser guidance to form multi-source collaborative tracking, ensuring that the welding head moves from the high temperature zone to the low temperature zone and realizing continuous welding.

[0035] 3. By combining laser thermal superposition effect with infrared temperature detection, it is possible to determine in real time whether the weld seam is misaligned during the welding process. This not only allows for timely detection of weld seam misalignment but also eliminates the need to pause the welding work. This avoids affecting the welding process and ensures the quality of the finished product after welding. Attached Figure Description

[0036] Figure 1 This is a flowchart illustrating an automatic welding seam tracking method for rectangular frames based on multi-source control, according to the present invention. Detailed Implementation

[0037] The invention will now be further described with reference to the accompanying drawings.

[0038] As attached Figure 1 , one A method for automatic welding seam tracking of rectangular frames based on multi-source control, comprising:

[0039] Construct a welding guide line, clamp the workpiece with a fixture, attach several linear laser emitters to the surface of the workpiece, and control and adjust the attitude of each linear laser emitter so that the linear lasers emitted by at least two linear laser emitters converge at the weld seam on the workpiece.

[0040] The welding head position is calibrated by identifying the location of the linear laser using a laser sensor mounted on the end of the welding robot arm, and guiding the welding head of the welding robot arm to move towards the location of the linear laser until the welding head of the welding robot arm is directly facing the linear laser.

[0041] The welding point position is calibrated so that the laser emitted by the cylindrical laser emitter mounted on the end of the welding robot arm forms a projection circle on the surface of the workpiece. The cylindrical laser emitter guides the welding head of the welding robot arm to move to one end of the linear laser, that is, the projection circle formed by the laser emitted by the cylindrical laser emitter is directly opposite one end of the linear laser. During welding, the intersection of the projection circle and the linear laser is the positive welding point, that is, the welding point that needs to be welded at this moment.

[0042] Temperature guidance is constructed by detecting the temperature distribution on the surface of the workpiece by an infrared temperature imager installed around the workpiece or integrated into the end of the welding robot arm, identifying high-temperature and low-temperature zones in the temperature distribution, and guiding the welding head of the welding robot arm to move from the high-temperature zone to the low-temperature zone.

[0043] A multi-dimensional adjustment mechanism is constructed. By receiving detection data from the laser sensor and infrared temperature imager through the data processing and control module integrated in the welding robot control system, a multi-dimensional adjustment mechanism is formed, which includes linear laser guidance, projection spot calibration, and temperature distribution correction. The data processing and control module controls the movement of the welding head of the welding robot based on the final output of the multi-dimensional adjustment mechanism.

[0044] It is important to emphasize that the welding robotic arm operates under the control of the data processing and control module, which calculates the final structure based on a multi-source adjustment mechanism. Whether the welding guide line is constructed using a linear laser or the temperature guide is constructed using an infrared temperature imager, both only provide guidance for the welding robotic arm; hence the term "guidance." However, this "guidance" refers to a direction, not control. Therefore, all movements of the welding robotic arm are controlled by the data processing and control module, not by the linear laser emitter, laser sensor, cylindrical laser emitter, or infrared temperature imager.

[0045] Furthermore, in the embodiments described in this invention, the workpieces to be welded are two adjacent beams of a rectangular frame, and these two beams are perpendicular to each other after splicing. Therefore, the weld seam described in this solution is the splicing gap corresponding to the right angle of the two welded parts, and there are splicing gaps on both the outer and inner sides of the rectangular frame after splicing. When the workpieces to be welded are placed on a work platform parallel to the horizontal plane, the weld seam extends vertically in a direction perpendicular to the horizontal plane. That is, the welding head of the welding robot arm also needs to move along a vertical movement trajectory that coincides with the weld seam. Therefore, it is necessary to alleviate the frequent adjustment of the robot arm's posture during the welding process, that is, to adjust the angle between the welding head and the horizontal plane. If it cannot be adjusted in time, it will cause motion interference between the end of the welding robot arm and the workpieces to be welded during the welding process (for example, the welding work between the three beams of the rectangular frame has been completed). In the process of welding the internal joint between the fourth beam and other beams, if the angle between the welding head of the welding robot and the horizontal plane remains constant, and the rectangular frame area is small enough, the welding head will collide with other beams that have already been welded during the welding process, and the end of the weld near the horizontal working platform cannot be welded. Therefore, compared with the common automatic welding technology where the weld is parallel to the horizontal plane, the embodiment of the present invention requires more precise tracking of the weld, so that the welding robot can adjust its posture more accurately and in a timely manner. Thus, whether the weld is perpendicular to the horizontal plane, parallel to the horizontal plane, or at an angle to the horizontal plane, the automatic welding weld tracking method for rectangular frames based on multi-source control described in the present invention can complete the welding task of the rectangular frame.

[0046] More specifically, constructing the welding guide includes:

[0047] Select a suitable linear laser emitter model based on parameters such as the material of the workpiece, the length of the weld, and the direction of extension.

[0048] Several linear laser emitters are installed on both sides of the weld along the length of the weld. Two linear laser emitters located on either side of the same point along the length of the weld are called a linear laser emitter group. The installation angle and height of each linear laser emitter are adjusted so that the linear lasers emitted by the two linear laser sensors in each group form an intersection point at any cross-section of the corresponding weld, and the line connecting all intersection points coincides with the center line of the weld. The linear lasers formed by each linear laser emitter group are connected sequentially to form a laser guide line. The extension direction of the laser guide line is the same as the extension direction of the weld of the workpiece. This laser guide line is called the welding guide line.

[0049] Adjust the frequency of each linear laser emitter and make the linewidth of the linear laser emitted by each linear laser emitter equal to the width of the weld.

[0050] More specifically, calibrating the weld joint position includes:

[0051] Select the appropriate laser sensor model based on the wavelength of the linear laser emitter.

[0052] During installation, the three-dimensional deviation data between the laser sensor and the end of the welding head (i.e., the end that contacts the workpiece during welding) is recorded in the data processing and control module.

[0053] After projecting linear lasers onto the weld seam using various linear laser emitters, a three-dimensional spatial coordinate system is established with the location of the welding head end as the origin, the X-axis along the weld seam extension direction as the X-axis, the axis of the welding head as the Z-axis (the direction in which the welding head points towards the surface of the workpiece), and the direction perpendicular to the plane formed by the X-axis and Z-axis as the Y-axis. In the welding preparation stage, the Z-axis is the line connecting the welding head to any end of the linear laser, the X-axis is the line connecting the beginning and end of the weld seam, and the Y-axis is the width direction of the weld seam.

[0054] After establishing a three-dimensional spatial coordinate system, the three-dimensional deviation data between the laser sensor and the welding head end are substituted into the spatial coordinate system to calculate the coordinate information of the laser sensor in the spatial coordinate system.

[0055] The laser sensor collects the contour information of the linear laser emitted by the linear laser emitter in real time and transmits it to the data processing and control module. The data processing and control module can convert this contour information into three-dimensional coordinate data and calculate the three-dimensional coordinate data of the center line of the linear laser contour.

[0056] During the welding preparation stage, the data processing module calculates the deviation between the current welding head position and the linear laser position. Specifically, it calculates the deviation between the linear laser position and the origin on the X and Y axes in the spatial coordinate system. Based on the deviation calculation results, the posture of the welding robot arm is adjusted so that the welding head of the welding robot arm is directly facing the plane of the linear laser. In other words, the Z axis of the spatial coordinate system is perpendicular to the plane formed by the X and Y axes, and the axis of the welding head of the welding robot arm is perpendicular to the center line of the linear laser profile.

[0057] More specifically, calibrating the solder joint location includes:

[0058] Based on parameters such as the material of the workpiece, the length of the weld, and the direction of extension, a suitable linear laser emitter model is selected. The laser color emitted by the cylindrical laser emitter is different from that emitted by the linear laser emitter. Based on the wavelength of the cylindrical laser emitter, a suitable laser sensor model is selected. That is, the laser sensor described in this invention is equipped with multispectral laser imaging technology, which can simultaneously identify lasers of multiple colors.

[0059] Adjust the installation angle of the adjustable cylindrical laser emitter so that its laser projection direction is consistent with the welding direction of the welding head.

[0060] Adjust the power of the adjustable cylindrical laser emitter so that the diameter of the projected spot circle formed by the laser emitted by the cylindrical laser emitter on the workpiece is equal to the width of the weld, that is, the diameter of the projected spot circle is equal to the line width of the linear laser.

[0061] The laser sensor collects the contour information of the spot circle within the linear laser profile emitted by the cylindrical laser emitter in real time, and transmits it to the data processing and control module. The data processing and control module can convert this contour information into three-dimensional coordinate data and calculate the three-dimensional coordinate data of the spot circle contour.

[0062] During the welding preparation stage, the laser emitted by the cylindrical laser emitter is projected onto one end of the linear laser, i.e., the three-dimensional coordinate data of the spot outline is the same as the three-dimensional coordinate data of one end of the linear laser outline. It should be emphasized here that in the embodiments of this invention, setting the weld width, the diameter of the projected spot, and the linewidth of the linear laser to be equal is only for the convenience of introducing the working principle of this scheme, and does not mean that it is necessary to ensure that the three are the same in actual implementation. In practical applications, it is only necessary to ensure that the centerline of the weld and the centerline of the linear laser coincide, and to ensure that the center of the projected spot is located on the centerline of the weld. In general, the linewidth of the linear laser can be greater than or less than the width of the weld, while the diameter of the projected spot is equal to the width of the weld.

[0063] During the welding process, the linear laser emitted by the linear laser emitter and the projection ring formed by the cylindrical laser emitter work together. The data processing and control module guides the welding path of the welding arm's welding head based on the detection results of the laser sensor, thereby guiding and controlling the welding head of the welding arm to gradually move from one end of the linear laser to the other. Specifically, by adjusting the posture of the welding arm, the three-dimensional coordinate data of the projection ring contour is sequentially aligned with all the three-dimensional coordinate data of the linear laser contour, and the three-dimensional coordinate data of the projection ring contour is different each time. This allows the welding head of the welding arm to gradually move from one end of the linear laser to the other, thus enabling continuous welding. That is, the three-dimensional coordinate data of the spot ring contour is changed by the three-dimensional coordinate data of the linear laser contour. More specifically, the projection area of ​​the linear laser emitter on the surface of the workpiece can be regarded as a large rectangular area, while the projection area of ​​the cylindrical laser emitter on the surface of the workpiece can be regarded as a smaller rectangular area. The width of the smaller rectangular area is equal to that of the larger rectangular area, but the length of the smaller rectangular area is much smaller than that of the larger rectangular area. The smaller rectangular area is translated along the length direction within the larger rectangular area, and the translation distance is the length of the smaller rectangular area each time. When the total translation distance of the smaller rectangular area is equal to the length of the larger rectangular area, the welding task is considered to be completed.

[0064] More specifically, building a temperature-guided system includes:

[0065] During the welding preparation stage, the infrared temperature imager monitors the temperature distribution of the workpiece in real time. Because the projected surface absorbs the energy generated by the laser after projection and forms a thermal field, and multiple lasers irradiate the same point, a stacking effect occurs, meaning the temperature at that point is higher than the temperature when only one laser irradiates it. As explained above, during the welding preparation stage, the laser emitted by the cylindrical laser emitter is projected onto the end of the linear laser beam. Therefore, the temperature at that end is higher than other areas projected by the linear laser beam. Consequently, in the thermal image of the temperature distribution detected by the infrared temperature imager, a temperature distribution will also be present. The highest temperature point; more specifically, assuming that during the welding preparation stage, the temperature of the linear laser projection area is the first temperature, and the temperature of the projection area of ​​the projection spot is the second temperature, the second temperature is higher than the first temperature, and the distribution range of the second temperature is within the distribution range of the first temperature; the infrared temperature imager transmits its detection results to the data processing and control module, and the data processing and control module can couple the detection results of the infrared temperature imager with the detection results of the laser sensor, thereby ensuring that the projection spot formed by the laser emitted by the cylindrical laser emitter on the surface of the workpiece is always within the linear range formed by the linear laser on the surface of the workpiece.

[0066] During the welding process, the infrared temperature imager monitors the temperature distribution of the workpiece in real time. The weld seam of the workpiece is divided along the welding direction into welded points, positive weld points, and unwelded points. The welded and unwelded points are located on either side of the positive weld point, with the unwelded point in front of the weld direction. Because the contact point between the welding head of the welding robot and the surface of the workpiece generates extremely high temperatures during welding, and the temperature of the weld point does not immediately decrease after welding, the welded, positive weld, and unwelded points respectively form a residual heat zone, a high-temperature zone, and a low-temperature zone in the thermal image detected by the infrared temperature imager. Furthermore, since the welded points have just finished welding, the temperature in the residual heat zone is high. The infrared temperature imager transmits its detection results to the data processing and control module. The data processing and control module uses the distribution of residual temperature zone, high temperature zone, and low temperature zone in the temperature distribution thermal image to form temperature guidance and control the welding head of the welding robot arm to move from the high temperature zone to the low temperature zone. More specifically, each time welding is performed, the positions of the residual temperature zone, high temperature zone, and low temperature zone in the infrared temperature imager will change. The position of the low temperature zone in the previous welding process is the position of the high temperature zone in the next welding process, and the position of the high temperature zone in the previous welding process is the position of the residual temperature zone in the next welding process.

[0067] The high temperatures generated during welding can easily cause the workpiece to expand, leading to weld misalignment. Specifically, the weld width can easily increase due to the deformation caused by the high-temperature expansion of the workpiece. In this situation, the welding head of the robotic arm may only contact one side of the workpiece during welding, or not at all, resulting in significant errors or even non-compliance with standards in the finished product. Current technologies typically use image recognition sensors to directly identify whether the weld width has changed. However, this detection method requires pausing welding until the detection and adjustment are completed, thus affecting processing efficiency. Furthermore, this method has limitations; it can only be used for welding tasks that do not produce smoke during the welding process and cannot be applied to all welding tasks.

[0068] In some embodiments applicable to this invention, the linewidth of the linear laser emitted by the linear laser emitter is slightly larger than the width of the weld, and the diameter of the projection spot formed by the cylindrical laser emitter on the weld is equal to the width of the weld. Since the linewidth of the linear laser emitted by the linear laser emitter and the diameter of the projection spot formed by the cylindrical laser emitter do not change during the welding process, and their projection positions do not change, and due to the thermal superposition effect, the infrared temperature imager can still form the distribution range of the first temperature and the distribution range of the second temperature in the temperature distribution thermal image during the welding process (here, the first and second temperatures are both higher than the state described in the welding preparation stage). If during the processing... If, in the thermal image of temperature distribution detected by the mid-infrared temperature imager, there is no distribution area of ​​the second temperature within the distribution range of the first temperature, then the weld is determined to be offset, and welding needs to be stopped and the clamping state of the fixture holding the workpiece adjusted. More specifically, if the width of the weld increases during the welding process, the laser emitted by the cylindrical laser emitter will pass directly through the gap of the weld instead of being projected onto the weld. Therefore, only a portion of the linear laser will be projected onto the surface of the workpiece, and thus the thermal image of temperature distribution detected by the infrared temperature imager will not contain the thermal image corresponding to the second temperature. Therefore, it is only necessary to determine in real time whether there is a thermal image corresponding to the second temperature in the thermal image detected by the infrared temperature imager, without needing to stop welding and then check.

[0069] It is important to emphasize that, as those skilled in the art should know, the weld seam mentioned here generally refers to the weld filler area formed after two welded parts are joined together. It includes a gap and the base materials of the two welded parts on both sides of this gap. Therefore, the projection areas of the linear laser and the projection spot are both weld filler areas, not gaps. The weld seam offset discussed above, in certain embodiments to which this invention applies, is caused by the increase in the gap width in the weld filler area due to thermal expansion. A certain error is allowed in the welding process, that is, the width of this gap has a maximum allowable width value. Therefore, in this part, the diameter of the projection spot formed by the cylindrical laser emitter should be equal to the maximum allowable width value of the gap. Therefore, if the width of the gap in the weld filler area is less than the maximum allowable width value, the infrared temperature imager can detect the thermal image of the second temperature. If the width of the gap in the weld filler area is equal to or greater than the maximum allowable width value, the laser emitted by the cylindrical laser emitter will pass directly through this gap, and the infrared temperature imager will not be able to detect the thermal image of the second temperature.

[0070] The above are the preferred embodiments described in this invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention.

Claims

1. A multi-source control based rectangular frame automatic welding seam tracking method, characterized in that: include: Construct a welding guide line, attach several linear laser emitters to the surface of the workpiece, and control and adjust the attitude of each linear laser emitter so that the linear lasers emitted by at least two linear laser emitters converge at the weld seam on the workpiece. The welding head position is calibrated by identifying the location of the linear laser using a laser sensor mounted on the end of the welding robot arm, and guiding the welding head of the welding robot arm to move toward the location of the linear laser until the welding head of the welding robot arm is directly facing the linear laser. The welding point position is calibrated so that the laser emitted by the cylindrical laser emitter mounted on the end of the welding robot arm forms a projection circle on the surface of the workpiece. The cylindrical laser emitter guides the welding head of the welding robot arm to move to one end of the linear laser, that is, the projection circle formed by the laser emitted by the cylindrical laser emitter is directly opposite one end of the linear laser. During welding, the intersection of the projection circle and the linear laser is the positive welding point, that is, the welding point that needs to be welded at this moment. Temperature guidance is constructed by detecting the temperature distribution on the surface of the workpiece by an infrared temperature imager installed around the workpiece or integrated into the end of the welding robot arm, identifying high-temperature and low-temperature zones in the temperature distribution, and guiding the welding head of the welding robot arm to move from the high-temperature zone to the low-temperature zone. A multi-dimensional adjustment mechanism is constructed. By receiving detection data from the laser sensor and infrared temperature imager through the data processing and control module integrated in the welding robot control system, a multi-dimensional adjustment mechanism is formed, which includes linear laser guidance, projection spot calibration, and temperature distribution correction. The data processing and control module controls the movement of the welding head of the welding robot based on the final output of the multi-dimensional adjustment mechanism.

2. The method of claim 1, wherein: The construction of the welding guide wire includes: Several linear laser emitters are installed on both sides of the weld along the length of the weld. Two linear laser emitters located on either side of the same point along the length of the weld are called a linear laser emitter group. The installation angle and height of each linear laser emitter are adjusted so that the linear lasers emitted by the two linear laser sensors in each group form an intersection point at any cross section of the corresponding weld, and the line connecting all intersection points coincides with the center line of the weld.

3. The method of claim 2, wherein: Adjust the frequency of each of the linear laser emitters, and make the linewidth of the linear laser emitted by each linear laser emitter equal to the width of the weld.

4. The method of claim 1, wherein: The calibration welding head position includes: During installation, the three-dimensional deviation data between the laser sensor and the welding head end is recorded in the data processing and control module; A three-dimensional spatial coordinate system is established, and the three-dimensional deviation data between the laser sensor and the welding head end is substituted into the spatial coordinate system to calculate the coordinate information of the laser sensor in the spatial coordinate system. The laser sensor collects the contour information of the linear laser emitted by the linear laser emitter in real time and transmits it to the data processing and control module. The data processing and control module can convert this contour information into three-dimensional coordinate data and calculate the three-dimensional coordinate data of the center line of the linear laser contour.

5. A multi-source control based rectangular frame automatic weld seam tracking method according to claim 4, characterized in that: The method for establishing the three-dimensional spatial coordinate system includes: Set the position of the welding head end as the origin of the three-dimensional spatial coordinate system; Set the weld extension direction as the X-axis; The axis of the welding head is set as the Z axis; The direction of the plane formed by the vertical X axis and the Z axis is set as the Y axis.

6. A multi-source control based rectangular frame automatic weld seam tracking method according to claim 5, characterized in that: The data processing module calculates the deviation between the position of the welding head and the position of the linear laser, i.e. the deviation between the position of the linear laser and the origin in the spatial coordinate system in the X axis and the Y axis, and adjusts the posture of the welding robot according to the deviation calculation result, so that the welding head of the welding robot is perpendicular to the plane where the linear laser is located, i.e. the Z axis of the spatial coordinate system is perpendicular to the plane formed by the X axis and the Y axis, and the axis of the welding head of the welding robot is perpendicular to the center line of the linear laser profile.

7. The method of claim 1, wherein: The calibration of the welding point position includes: Adjusting the mounting angle of the cylindrical laser emitter so that the laser projection direction is consistent with the welding direction of the welding head; Adjusting the power of the cylindrical laser emitter, and making the diameter of the projection spot circle formed on the workpiece by the laser emitted by the cylindrical laser emitter equal to the width of the weld, i.e. the diameter of the projection spot circle is equal to the linear laser line width; The laser sensor collects the profile information of the spot circle in the linear laser profile in real time, and transmits it to the data processing and control module, which can convert the profile information into three-dimensional coordinate data and calculate the three-dimensional coordinate data of the spot circle profile; During the welding preparation stage, the laser emitted by the cylindrical laser emitter is projected on the end of the linear laser, i.e. the three-dimensional coordinate data of the spot circle profile is the same as the three-dimensional coordinate data of one end of the linear laser profile.

8. The method of claim 7, wherein: During the welding process, the linear laser emitted by the linear laser emitter and the projection spot circle formed by the cylindrical laser emitter cooperate with each other, and the data processing and control module forms a laser guide for the welding path of the welding head of the welding robot according to the detection result of the laser sensor, so as to guide and control the welding head of the welding robot to move from one end of the linear laser to the other end.

9. The method of claim 1, wherein: The temperature guide includes: The infrared temperature imager detects the temperature distribution of the workpiece in real time; During the welding process, the weld on the workpiece is divided into welded points, welding points and unwelded points along the welding direction, the welded points and unwelded points are located on both sides of the welding points, and the unwelded points are located in front of the welding direction; the welded points, welding points and unwelded points form residual temperature zones, high temperature zones and low temperature zones in the temperature distribution thermal image detected by the infrared temperature imager, and the temperature of the residual temperature zone is higher than that of the low temperature zone; the infrared temperature imager transmits the detection result to the data processing and control module, and the data processing and control module forms a temperature guide through the distribution of the residual temperature zone, the high temperature zone and the low temperature zone in the temperature distribution thermal image, and controls the welding head of the welding robot to move from the high temperature zone to the low temperature zone.

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