An automatic tracking welding method for arc-shaped steel

Abstract

The present application relates to the field of welding, especially to an automatic tracking welding method for arc-shaped steel, comprising: obtaining an arc trajectory graph and a three-dimensional distribution area of protective gas through welding test; monitoring the welding position change amount in the first period according to the arc trajectory graph, and adjusting the welding gun elongation length according to the welding position change amount; determining the actual coverage area of the protective gas based on the arc position change area and the protective gas projection area, and adjusting the protective gas flow according to the area change amount of the actual coverage area of the protective gas; in the actual welding, further monitoring the cooling rate of the molten pool edge in the second period, and adjusting the protective gas flow according to the cooling rate of the molten pool edge, effectively solving the problem of unstable gas coverage effect caused by the temperature fluctuation of the molten pool, and improving the weld forming quality and process stability of the automatic tracking welding of the arc-shaped steel.

Description

Technical Field

[0001] This invention relates to the field of welding technology, and in particular to an automatic tracking welding method for curved steel. Background Technology

[0002] With the continuous development of modern industrial manufacturing technology, curved steel structures are increasingly widely used in shipbuilding, pressure vessels, pipeline engineering, and large building frames. As a key process for connecting curved components, the welding quality of curved steel directly affects the strength, sealing, and service life of the overall structure. However, due to the unique curved surface geometry of curved steel, the welding torch posture needs to be adjusted in real time according to the weld trajectory during the welding process. Traditional manual welding methods struggle to guarantee the consistency and stability of welding parameters, and require extremely high skill levels from operators, resulting in high labor intensity and low production efficiency.

[0003] In recent years, automated welding technology has developed rapidly. Automated tracking welding systems, through visual sensing, laser tracking, or arc sensing, achieve automatic identification and tracking of weld trajectories, significantly improving the automation level of welding operations. However, in the practical application of arc-shaped steel welding, many technical challenges remain: On the one hand, the curvature variation of the arc weld leads to complex molten pool flow characteristics. Under the combined action of gravity, surface tension, and arc force, the molten pool metal is prone to flowing or shifting, resulting in poor weld formation. On the other hand, uneven distribution of welding heat input makes it difficult to control the cooling rate at the edge of the molten pool. If cooling is too fast, the molten pool metal lacks fluidity, easily producing defects such as incomplete fusion and undercut; if cooling is too slow, it leads to problems such as molten pool collapse and burn-through. In addition, existing automated tracking welding methods mostly use fixed shielding gas flow parameters, failing to adjust in real time according to the dynamic changes of the molten pool, making it difficult to adapt to the rapid changes in thermal circulation conditions during arc-shaped steel welding, thus restricting further improvement in welding quality.

[0004] Therefore, there is an urgent need to develop an automatic tracking welding method that can adjust welding parameters, especially the protective gas flow rate, in real time based on the state of the molten pool, in order to achieve high-quality and high-efficiency automated welding of curved steel. Summary of the Invention

[0005] To address this issue, the present invention provides an automatic tracking welding method for arc-shaped steel, which overcomes the problem in the prior art where the curvature change of the arc weld during arc welding leads to complex molten pool flow characteristics and unstable shielding gas coverage.

[0006] To achieve the above objectives, the present invention provides an automatic tracking welding method for curved steel, comprising: Welding tests were conducted on the welding position of the arc-shaped steel by controlling the welding torch. The three-dimensional distribution area of ​​the shielding gas at the welding position and the trajectory diagram of the electric arc of the curved steel were obtained respectively. The change in welding position of the arc within the first monitoring period is determined based on the arc trajectory diagram. Adjust the welding torch extension length according to the change in the welding position of the arc during the first monitoring cycle; Based on the arc trajectory diagram, the area of ​​change in the welding position of the arc on the arc-shaped steel welding surface during the first monitoring period is determined; The actual coverage area of ​​the shielding gas on the welding position is determined based on the variation area and the three-dimensional distribution area of ​​the shielding gas; The flow rate of the protective gas is determined based on the area of ​​the actual coverage area; The welding torch is used to weld the arc-shaped steel at the welding position according to the extension length of the welding torch and the flow rate of the shielding gas. Obtain the cooling rate of the molten pool edge during the second monitoring cycle in the actual welding process; The flow rate of the protective gas is re-determined based on the cooling rate at the edge of the molten pool; Welding continues at the welding positions of the arc-shaped steel according to the redefined flow rate of the protective gas to complete the automatic tracking welding.

[0007] Further, adjusting the welding torch extension length based on the change in the welding position of the arc during the first monitoring cycle includes: The amount of change in welding position is compared with a preset threshold for the amount of change in welding position; If the change in welding position is less than the preset threshold for the change in welding position, it is determined that the degree of interference of the magnetic field of the arc steel on the electric arc meets the requirements. If the change in welding position is greater than or equal to a preset threshold for the change in welding position, it is determined that the magnetic field of the arc steel does not meet the requirements for the interference of the arc, and the extension length of the welding torch is reduced according to the difference between the change in welding position and the preset threshold for the change in welding position.

[0008] Furthermore, the change in welding position is the straight-line distance between the contact point between the electric arc and the welding surface of the arc-shaped steel at the start of the first monitoring period and the contact point between the electric arc and the welding surface of the arc-shaped steel at the end of the monitoring period.

[0009] Furthermore, the reduction in the welding torch elongation is positively correlated with the difference between the welding position change and the preset welding position change threshold.

[0010] Furthermore, the area of ​​change in the welding position is the three-dimensional spatial area occupied by the electric arc above the welding surface of the arc-shaped steel at all monitoring moments within the first monitoring cycle.

[0011] Furthermore, the actual coverage area of ​​the shielding gas at the welding position is the first projection area excluding the second projection area. Wherein, the first projection area is the projection area of ​​the three-dimensional distribution area of ​​the protective gas onto the arc-shaped steel welding surface; the second projection area is the projection area of ​​the changing area onto the arc-shaped steel welding surface.

[0012] Further, determining the flow rate of the protective gas based on the area of ​​the actual coverage area includes: Compare the area of ​​the actual coverage area with the preset area; If the actual covered area is smaller than the preset area, the protective gas coverage of the molten pool is deemed qualified. If the area of ​​the actual covered area is greater than or equal to the preset area, it is determined that the protective gas coverage of the molten pool is unqualified, and the flow rate of the protective gas is increased according to the difference between the change and the preset area. The increase in the protective gas flow rate is positively correlated with the difference between the change and the preset area.

[0013] Furthermore, the area of ​​the actual covered area is the difference between the curved surface area of ​​the first projected area and the curved surface area of ​​the second projected area on the arc-shaped steel welding surface.

[0014] Furthermore, the flow rate of the protective gas is redetermined based on the cooling rate at the edge of the molten pool, including: The cooling rate is compared with a preset cooling rate threshold. If the cooling rate is less than a preset cooling rate threshold, it is determined that the impact of the protective gas on the molten pool exceeds the allowable range, and the flow rate of the protective gas is reduced according to the difference between the preset cooling rate threshold and the cooling rate. If the cooling rate is greater than or equal to the preset cooling rate threshold, it is determined that the shielding gas flow rate meets the welding quality requirements, and the current shielding gas flow rate is maintained to continue welding. The reduction in the protective gas flow rate is positively correlated with the difference between the preset cooling rate threshold and the cooling rate.

[0015] Furthermore, the cooling rate of the edge of the molten pool is the ratio of the difference between the average temperature at the end of a unit monitoring cycle and the average temperature at the beginning of a unit monitoring cycle in the recessed area formed by the same predetermined length recessed within the outline of the current molten pool, to the duration of the unit monitoring cycle. Wherein, the average temperature at the end of the unit monitoring cycle is the ratio of the sum of all temperature values ​​of all temperature monitoring points in the recessed area at the end of the unit monitoring cycle to the total number of temperature monitoring points; the average temperature at the beginning of the unit monitoring cycle is the ratio of the sum of all temperature values ​​of all temperature monitoring points in the recessed area at the beginning of the unit monitoring cycle to the total number of temperature monitoring points.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention monitors the changes in the arc trajectory during welding tests and adjusts the extension length of the welding torch to suppress the magnetic blow interference of the magnetic field of the arc steel structure on the arc, thus ensuring arc stability; at the same time, based on the precise spatial analysis of the welding position change area and the three-dimensional distribution area of ​​the shielding gas, the actual coverage area is determined and the shielding gas flow rate is adjusted accordingly, thus achieving precise coverage of the molten pool by the shielding gas; by monitoring the cooling rate at the edge of the molten pool to form a feedback adjustment mechanism, the shielding gas flow rate is optimized a second time, effectively solving the problem of unstable gas coverage caused by molten pool temperature fluctuations, and improving the weld formation quality and process stability of automatic tracking welding of arc steel.

[0017] Furthermore, by reducing the welding torch extension length based on the change in the welding position of the arc, when the grounding wire of the welding torch is not set accurately, or when residual magnetism appears in the arc steel, or when the magnetic field generated by the welding wire is unevenly distributed on the arc steel, the residual magnetism in the arc steel causes the arc to deviate. By shortening the welding torch extension length to shorten the current loop, the influence of the magnetic field in the arc steel on the actual welding position and arc direction of the welding torch arc is reduced, so that the arc can act more stably on the target welding position, laying the foundation for subsequent precise control of the shielding gas coverage.

[0018] Furthermore, the actual coverage area is determined based on the spatial relationship between the welding position change area and the three-dimensional distribution area of ​​the shielding gas. This allows for the accurate identification of the welding area effectively covered by the shielding gas, the identification of the ineffective coverage area caused by arc deviation, and the changes in the flow field of the shielding gas caused by the curvature of the arc steel, which result in a decrease in the isolation and protection effect on the molten pool generated at the welding position, thus avoiding distortion of the gas coverage assessment due to arc instability.

[0019] Furthermore, the protective gas flow rate is determined based on the change in the actual coverage area. This establishes a correlation between the protective gas coverage effect and the gas flow rate. When the actual coverage area fluctuates due to arc offset or changes in the curvature of the curved steel, the area of ​​the actual coverage area is calculated using the first and second projection areas. Based on this area, the protective gas flow rate is precisely increased, thereby reducing the combined impact of the protective gas loss due to arc and the shape of the curved steel on the reduced protective area of ​​the molten pool. This further improves the accuracy of the protective gas flow rate and the accuracy of the molten pool protection.

[0020] Furthermore, the shielding gas flow rate is re-determined based on the cooling rate at the edge of the molten pool. If the shielding gas flow rate is too high, the edge of the molten pool will cool too quickly, forming a small undercut at the arc termination position, which will lead to a decrease in weld strength. Therefore, by increasing the shielding gas flow rate and then decreasing it, a balance is achieved between the shielding gas protection range and the uniformity of molten pool cooling. Attached Figure Description

[0021] Figure 1 This is a flowchart of an automatic tracking welding method for curved steel according to an embodiment of the present invention; Figure 2 This is a flowchart illustrating the process of adjusting the extension length of the welding torch according to an embodiment of the present invention. Figure 3 A flow chart of the protective gas flow rate is determined for embodiments of the present invention; Figure 4 The flow chart of the protective gas flow rate was redefined for this embodiment of the invention; Figure 5 This is a side view of the automatic tracking welding process of arc-shaped steel according to an embodiment of the present invention; In the diagram: 1. Curved steel; 2. Molten pool; 3. Three-dimensional distribution area of ​​protective gas; 4. Electric arc. Detailed Implementation

[0022] To make the objectives and advantages of the present invention clearer, the present invention will be further described below with reference to embodiments; it should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention.

[0023] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0024] Please see Figure 1-5The figures shown are, respectively, a flowchart of the automatic tracking welding method for arc-shaped steel according to an embodiment of the present invention, a flowchart of adjusting the welding torch extension length, a flowchart of determining the flow rate of the shielding gas, a flowchart of re-determining the flow rate of the shielding gas, and a side view of the automatic tracking welding process for arc-shaped steel.

[0025] An embodiment of the present invention provides an automatic tracking welding method for curved steel, comprising: Step S1: Control the welding torch to perform welding tests on the welding position of the arc-shaped steel 1; Step S2: Obtain the three-dimensional distribution area 3 of the shielding gas at the welding position and the trajectory diagram of the arc 4 of the arc steel 1, respectively. Step S3: Determine the change in welding position of arc 4 within the first monitoring cycle based on the trajectory diagram of arc 4; Step S4: Adjust the welding torch extension length according to the change in welding position of arc 4 during the first monitoring cycle. Step S5: Based on the trajectory diagram of the electric arc 4, determine the area of ​​change in the welding position of the electric arc 4 on the welding surface of the arc-shaped steel 1 during the first monitoring period; Step S6: Determine the actual coverage area of ​​the shielding gas on the welding position based on the changed area and the three-dimensional distribution area 3 of the shielding gas; Step S7: Determine the flow rate of the protective gas based on the area of ​​the actual coverage area; Step S8: Control the welding torch to perform actual welding on the welding position of the arc-shaped steel 1 according to the extension length of the welding torch and the flow rate of the shielding gas; Step S9: Obtain the cooling rate of the molten pool edge during the second monitoring cycle in the actual welding process; Step S10: Re-determine the flow rate of the protective gas based on the cooling rate at the edge of the molten pool; Step S11: Continue welding the arc-shaped steel at the welding position according to the newly determined flow rate of the protective gas to complete the automatic tracking welding.

[0026] Specifically, the weld center trajectory coordinates are determined by scanning the weld surface contour image using a line laser sensor. The line laser sensor scans along the weld direction to acquire laser band images at the weld cross-section. After grayscale processing, the upper and lower edge feature points of the laser band are extracted to obtain continuous weld center trajectory coordinates. The bending characteristics of the arc-shaped steel 1 are identified by calculating the curvature changes of adjacent scanning points, and the curvature abrupt change points are marked as trajectory key points, establishing a three-dimensional spatial coordinate sequence of the weld center trajectory. The robotic arm controls the welding torch to move to the starting welding position of the arc-shaped steel 1 according to the three-dimensional spatial coordinate sequence. The welding test is a short-term pre-welding operation performed before the formal welding. Its purpose is to obtain real-time parameter feedback during the welding process, including the arc 4 shape, shielding gas distribution, and initial response characteristics of the molten pool 2, providing a data basis for the precise adjustment of subsequent welding parameters. The first monitoring period is the duration of the welding test, which is set according to the curvature radius and plate thickness of the arc-shaped steel 1 and controlled within 10s-15s. The test current is 90% of the formal welding current to avoid excessive heat impact on the base material.

[0027] Specifically, acquiring the three-dimensional distribution region 3 of the shielding gas at the welding position and the trajectory map of the arc 4 of the curved steel 1 respectively includes: real-time acquisition of the velocity field distribution data of the shielding gas in the welding space using a multi-channel gas flow sensor array arranged around the welding torch nozzle. The multi-channel gas flow sensor array includes 8 to 12 miniature thermal flow sensors evenly distributed along the circumference of the nozzle, reconstructing the three-dimensional flow field distribution of the shielding gas, and thus determining the boundary of the three-dimensional distribution region 3 of the shielding gas. The three-dimensional flow field reconstruction is based on a flow field order reduction model and a radial basis function interpolation method, using sensor measurements as boundary conditions, and reconstructing the continuous spatial distribution under the assumption of axisymmetry; the boundary of the distribution region is defined as an isosurface with a shielding gas volume fraction of 80%, reflecting the effective gas protection range.

[0028] Meanwhile, by using an industrial high-speed camera installed behind the welding torch and a narrow-band filter, combined with the spatial calibration relationship between the welding torch and the workpiece, the coordinates of the contact point between the root of the electric arc 4 and the welding surface of the arc-shaped steel 1 are calculated, thus forming the trajectory diagram of the electric arc 4.

[0029] Specifically, adjusting the welding torch extension length based on the change in welding position of arc 4 within the first monitoring cycle includes: The amount of change in welding position is compared with a preset threshold for the amount of change in welding position; If the change in welding position is less than the preset threshold for the change in welding position, it is determined that the degree of interference of the magnetic field of the arc steel 1 on the electric arc 4 meets the requirements. If the change in welding position is greater than or equal to the preset threshold for the change in welding position, it is determined that the interference of the magnetic field of the arc steel 1 on the arc 4 does not meet the requirements, and the extension length of the welding torch is reduced according to the difference between the change in welding position and the preset threshold for the change in welding position.

[0030] Specifically, the change in welding position is the straight-line distance between the contact point between the arc 4 and the welding surface of the arc-shaped steel 1 at the start of the first monitoring cycle and the contact point between the arc 4 and the welding surface of the arc-shaped steel 1 at the end of the monitoring cycle. The preset threshold for the change in welding position is set to 4.0 mm. This threshold is adjusted according to the radius of curvature and wall thickness of the arc-shaped steel 1. It should be noted that the data in this embodiment are all results obtained through preliminary experimental verification before the operation of the method described in this invention. Each preset value can be adjusted according to the specific application, as long as the method described in this invention can clearly define different specific situations in the single-item judgment process through the acquired values.

[0031] Specifically, the reduction in the welding torch elongation is positively correlated with the difference between the change in welding position and a preset threshold for the change in welding position. This positive correlation can be linear or nonlinear, and is not specifically limited. The slope of a linear positive correlation is also not limited and can be set according to the actual preparation conditions. The key requirement is that the larger the difference between the change in welding position and the preset threshold for the change in welding position, the greater the reduction in the welding torch elongation. For example, if the reduction in the welding torch elongation is set to ΔM, and the difference between the change in welding position and the preset threshold for the change in welding position is set to Δμ, then ΔM = γ × Δμ + M0, where γ is the length adjustment coefficient (set to 1.16), and M0 is the length compensation reference value (set to 2cm).

[0032] Specifically, the area of ​​change in welding position is the three-dimensional space occupied by the electric arc 4 above the welding surface of the arc-shaped steel 1 at all monitoring moments within the first monitoring cycle.

[0033] Specifically, the actual coverage area of ​​the shielding gas at the welding position is the first projection area excluding the second projection area; Wherein, the first projection area is the projection area of ​​the three-dimensional distribution area 3 of the protective gas onto the welding surface of the arc-shaped steel 1; the second projection area is the projection area of ​​the changing area onto the welding surface of the arc-shaped steel 1. This configuration, by projecting the three-dimensional distribution area onto the welding surface to form the first projection area, can intuitively reflect the theoretical coverage range of the protective gas under static conditions; while the second projection area, formed by eliminating the projection of the changing area, effectively eliminates disturbance factors within the heat-affected zone of the arc 4, making the calculated result of the actual coverage area more consistent with the actual control requirements of welding quality.

[0034] Specifically, an evaluation index for the adequacy of shielding gas coverage can be constructed based on the ratio of the actual coverage area to the area of ​​the change in the welding position. When this ratio is within a preset reasonable range, it indicates that the shielding gas's protective effect on the molten pool 2 and its surrounding heat-affected zone meets the process requirements; if the ratio is below the lower threshold, it indicates a risk of insufficient gas coverage, which may lead to defects such as weld oxidation and porosity. In this case, the shielding gas flow rate needs to be adjusted.

[0035] Specifically, determining the flow rate of the protective gas based on the area of ​​the actual coverage area includes: Compare the area of ​​the actual coverage area with the preset area of ​​the actual coverage area; If the area is smaller than the preset area, it is determined that the protective gas covers the molten pool 2 satisfactorily. If the area is greater than or equal to the preset area, it is determined that the protective gas coverage of the molten pool 2 is unqualified, and the protective gas flow rate is adjusted according to the difference between the area and the preset area.

[0036] Specifically, the preferred embodiment of the preset area is 0.4m2.

[0037] Specifically, the increase in the protective gas flow rate is positively correlated with the difference between the change and the preset area. It is understood that the positive correlation can be linear or nonlinear, and is not specifically limited. The slope of the linear positive correlation is also not specifically limited and can be set according to the actual preparation conditions, as long as the increase in the protective gas flow rate is greater than the difference between the change and the preset area. For example, if the increase in the protective gas flow rate is set as ΔT, and the difference between the change and the preset area is set as Δλ, then ΔT = α × Δλ + T0, where α is the flow rate adjustment coefficient, set to 1.12, and T0 is the flow rate compensation reference value, set to 2.5 L / min.

[0038] Specifically, the step of controlling the welding torch to actually weld the arc-shaped steel 1 according to the welding torch extension length and the shielding gas flow rate includes: after completing the parameter pre-adjustment within the first monitoring cycle, adjusting the welding torch extension length to the calculated target value, and simultaneously setting the shielding gas flow rate to the initial flow rate value determined based on the actual coverage area analysis, and starting the formal welding procedure.

[0039] Specifically, the flow rate of the protective gas is redetermined based on the cooling rate at the edge of the molten pool 2, including: The cooling rate is compared with a preset cooling rate threshold. If the cooling rate is less than the preset cooling rate threshold, it is determined that the adjustment of the protective gas flow rate is too large, resulting in slow cooling at the edge of the molten pool 2, and the protective gas flow rate is reduced according to the difference between the preset cooling rate threshold and the cooling rate. If the cooling rate is greater than or equal to a preset cooling rate threshold, it is determined that the shielding gas flow rate meets the welding quality requirements, and the current shielding gas flow rate is maintained to continue welding.

[0040] Specifically, the preset cooling rate threshold is set to 80℃ / s. This threshold takes into account the material properties, plate thickness and welding heat input conditions of the arc steel 1. The large flow rate of the protective gas leads to slow heat dissipation at the edge of the molten pool 2 and a low cooling rate, which in turn leads to the molten pool 2 cooling too slowly and is prone to collapse.

[0041] Specifically, the cooling rate at the edge of the molten pool 2 is monitored in real time by an array of temperature sensors arranged behind the direction of travel of the welding torch.

[0042] Specifically, the reduction in the protective gas flow rate is positively correlated with the difference between the preset cooling rate threshold and the cooling rate. It is understood that this positive correlation can be linear or nonlinear, and is not specifically limited. The slope of a linear positive correlation is also not specifically limited and can be set according to the actual preparation conditions, as long as the larger the difference between the preset cooling rate threshold and the cooling rate, the larger the reduction in the protective gas flow rate. For example, if the reduction in the protective gas flow rate is set to ΔF, and the difference between the preset cooling rate threshold and the cooling rate is set to Δσ, then ΔF = β × Δσ + F0, where β is the flow rate reduction conversion coefficient, set to 0.96, and F0 is the flow rate reduction compensation benchmark value, set to 0.5 L / min.

[0043] Furthermore, the cooling rate of the edge of the molten pool 2 is the ratio of the difference between the average temperature at the end of a unit monitoring cycle and the average temperature at the beginning of a unit monitoring cycle in the recessed area formed by the same predetermined length recessed within the outline of the current molten pool 2, to the duration of a unit monitoring cycle. Wherein, the average temperature at the end of the unit monitoring cycle is the ratio of the sum of all temperature values ​​of all temperature monitoring points within the recessed area at the end of the unit monitoring cycle to the total number of temperature monitoring points; the average temperature at the beginning of the unit monitoring cycle is the ratio of the sum of all temperature values ​​of all temperature monitoring points within the recessed area at the beginning of the unit monitoring cycle to the total number of temperature monitoring points. The unit monitoring cycle is set to a value ranging from 0.5 seconds to 1.5 seconds, preferably 1.0 second, to ensure a balance between the real-time performance and data stability of temperature monitoring; the predetermined length is set to a value ranging from 2 mm to 5 mm, preferably 3 mm.

[0044] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

[0045] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An automatic tracking welding method for curved steel, characterized in that, It includes: Welding tests were conducted on the welding position of the arc-shaped steel by controlling the welding torch. The three-dimensional distribution area of ​​the shielding gas at the welding position and the trajectory diagram of the electric arc of the curved steel were obtained respectively. The change in welding position of the arc within the first monitoring period is determined based on the arc trajectory diagram. Adjust the welding torch extension length according to the change in the welding position of the arc during the first monitoring cycle; Based on the arc trajectory diagram, the area of ​​change in the welding position of the arc on the arc-shaped steel welding surface during the first monitoring period is determined; The actual coverage area of ​​the shielding gas on the welding position is determined based on the variation area and the three-dimensional distribution area of ​​the shielding gas; The flow rate of the protective gas is determined based on the area of ​​the actual coverage area; The welding torch is used to weld the arc-shaped steel at the welding position according to the extension length of the welding torch and the flow rate of the shielding gas. Obtain the cooling rate of the molten pool edge during the second monitoring cycle in the actual welding process; The flow rate of the protective gas is re-determined based on the cooling rate at the edge of the molten pool; Welding continues at the welding positions of the arc-shaped steel according to the redefined flow rate of the protective gas to complete the automatic tracking welding.

2. The automatic tracking welding method for arc-shaped steel according to claim 1, characterized in that, The adjustment of the welding torch extension length based on the change in the welding position of the arc within the first monitoring cycle includes: The amount of change in welding position is compared with a preset threshold for the amount of change in welding position; If the change in welding position is less than the preset threshold for the change in welding position, it is determined that the degree of interference of the magnetic field of the arc steel on the electric arc meets the requirements. If the change in welding position is greater than or equal to a preset threshold for the change in welding position, it is determined that the magnetic field of the arc steel does not meet the requirements for the interference of the arc, and the extension length of the welding torch is reduced according to the difference between the change in welding position and the preset threshold for the change in welding position.

3. The automatic tracking welding method for arc-shaped steel according to claim 2, characterized in that, The change in welding position is the straight-line distance between the contact point between the electric arc and the welding surface of the arc-shaped steel at the start of the first monitoring period and the contact point between the electric arc and the welding surface of the arc-shaped steel at the end of the monitoring period.

4. The automatic tracking welding method for arc-shaped steel according to claim 3, characterized in that, The reduction in the welding torch elongation is positively correlated with the difference between the welding position change and the preset welding position change threshold.

5. The automatic tracking welding method for arc-shaped steel according to claim 4, characterized in that, The area of ​​change in welding position is the three-dimensional spatial region occupied by the electric arc above the welding surface of the arc-shaped steel at all monitoring moments within the first monitoring cycle.

6. The automatic tracking welding method for arc-shaped steel according to claim 5, characterized in that, The actual coverage area of ​​the shielding gas at the welding position is the first projection area excluding the second projection area. Wherein, the first projection area is the projection area of ​​the three-dimensional distribution area of ​​the protective gas onto the arc-shaped steel welding surface; the second projection area is the projection area of ​​the changing area onto the arc-shaped steel welding surface.

7. The automatic tracking welding method for arc-shaped steel according to claim 6, characterized in that, Determining the flow rate of the protective gas based on the area of ​​the actual coverage area includes: Compare the area of ​​the actual coverage area with the preset area; If the actual covered area is smaller than the preset area, the protective gas coverage of the molten pool is deemed qualified. If the area of ​​the actual coverage area is greater than or equal to the preset area, it is determined that the protective gas coverage of the molten pool is unqualified, and the flow rate of the protective gas is increased according to the difference between the change and the preset area. The increase in the flow rate of the protective gas is positively correlated with the difference between the change and the preset area.

8. The automatic tracking welding method for arc-shaped steel according to claim 7, characterized in that, The area of ​​the actual coverage area is the difference between the curved surface area of ​​the first projection area and the curved surface area of ​​the second projection area on the welded surface of the arc-shaped steel.

9. The automatic tracking welding method for arc-shaped steel according to claim 8, characterized in that, The flow rate of the protective gas is redetermined based on the cooling rate at the edge of the molten pool, including: The cooling rate is compared with a preset cooling rate threshold. If the cooling rate is less than a preset cooling rate threshold, it is determined that the impact of the protective gas on the molten pool exceeds the allowable range, and the flow rate of the protective gas is reduced according to the difference between the preset cooling rate threshold and the cooling rate. If the cooling rate is greater than or equal to the preset cooling rate threshold, it is determined that the shielding gas flow rate meets the welding quality requirements, and the current shielding gas flow rate is maintained to continue welding. The reduction in the protective gas flow rate is positively correlated with the difference between the preset cooling rate threshold and the cooling rate.

10. The automatic tracking welding method for arc-shaped steel according to claim 9, characterized in that, The cooling rate of the edge of the molten pool is the ratio of the difference between the average temperature at the end of a unit monitoring cycle and the average temperature at the beginning of a unit monitoring cycle in the recessed area formed by the same predetermined length within the outline of the current molten pool, to the duration of the unit monitoring cycle. Wherein, the average temperature at the end of the unit monitoring cycle is the ratio of the sum of all temperature values ​​of all temperature monitoring points in the recessed area at the end of the unit monitoring cycle to the total number of temperature monitoring points; the average temperature at the beginning of the unit monitoring cycle is the ratio of the sum of all temperature values ​​of all temperature monitoring points in the recessed area at the beginning of the unit monitoring cycle to the total number of temperature monitoring points.

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