Cold-formed section steel forming and welding method

Abstract

The invention relates to the technical field of section steel welding, in particular to a cold-formed section steel forming and welding method which comprises the following steps: S1, cleaning a welding position and nearby parts of cold-formed section steel, preheating the welding position by adopting a low-voltage high-current resistance heating mode after cleaning, and after the preheating treatment is finished, welding the cold-formed section steel by adopting a low-voltage high-current resistance heating mode; a soldering flux is smeared on the welding position, and a welding gun is used for conducting welding operation on the welding position; and S2, continuously collecting weld joint images through an industrial camera, fitting image data to obtain a surface contour image of a weld joint area, performing three-dimensional reconstruction on the surface contour image to obtain three-dimensional point cloud data of the weld joint area, evaluating the quality of the weld joint according to the three-dimensional point cloud data, and performing repair welding treatment on unqualified weld joints according to an evaluation result to obtain a repair welding result. According to the method, the problems that the welding effect is poor and the welding quality cannot be evaluated when the cold-formed section steel is welded in the prior art can be effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of cold-bent steel, in particular to a cold-bent steel forming and welding method. Background Art

[0002] Cold-formed steel, also known as steel cold-formed profiles or cold-formed profiles, refers to steel of various cross-sectional shapes and sizes that is made by bending hot-rolled or cold-rolled strip steel as a blank. However, the existing cold-formed steel welding method still has shortcomings. Specifically, the welding effect of the existing cold-formed steel is poor and the welding quality cannot be evaluated.

[0003] Therefore, a cold-bent steel forming and welding method is needed to solve the problems raised in the above background technology. Summary of the invention

[0004] The object of the present invention is to provide a cold-bent steel forming and welding method to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions: A cold-bent steel forming and welding method comprises the following steps: S1, clean the welding position and nearby parts of the cold-bent steel. After cleaning, preheat the welding position by low voltage and high current resistance heating. After the preheating treatment, apply flux to the welding position and use a welding gun to perform welding operations on the welding position; S2, continuously collecting weld images through an industrial camera, fitting the image data to obtain a surface profile image of the weld area, performing three-dimensional reconstruction on the surface profile image to obtain three-dimensional point cloud data of the weld area, evaluating the weld quality based on the three-dimensional point cloud data, performing repair welding on unqualified welds based on the evaluation results, and evaluating the secondary welds, and repeating the above operations until the weld quality meets the standard; S3, after welding is completed, remove the welding slag near the welding part of the cold-bent steel and keep the welded cold-bent steel at a temperature of 100℃-120℃ for 1h-2h. After the insulation is completed, cool it to room temperature at a rate of 2℃ / min-3℃ / min to obtain the welded cold-bent steel.

[0006] As a preferred solution of the present invention, the cleaning method of the welding position in S1 is to use sandpaper or a grinding wheel to grind the welding part of the cold-bent steel to remove the oxide film, use a dilute hydrochloric acid with a concentration of 1.2 mol / L and a dilute nitric acid with a concentration of 1 mol / L to mix in a volume ratio of 1:1.5 to prepare a cleaning solution, use the cleaning solution to clean the welding part of the cold-bent steel, and after cleaning, rinse with acetone and deionized water for 3-4 times in turn.

[0007] As a preferred solution of the present invention, the specific steps of the preheating treatment in S1 are to heat the welding area of ​​the cold-bent steel to 150°C-180°C by low voltage and high current resistance heating, the preheating current is 4.65kA-4.8kA, and the heating time is 5min-6min. After the heating is completed, the welding area of ​​the cold-bent steel is cooled to reduce its temperature to 100°C-120°C, and the welding area of ​​the cold-bent steel is heated again to rapidly increase the temperature to 170°C-190°C within 0.75s-1.75s, and then the welding alloy liquid is applied to the welding area of ​​the left cold-bent steel.

[0008] As a preferred solution of the present invention, the welding alloy liquid is made by mixing niobium metal powder, nickel metal powder, copper metal powder and acetone solvent in a mass ratio of 1:60:110:300, the viscosity of the welding alloy liquid is 0.88Pa·s-0.95Pa·s, and the coating thickness of the welding alloy liquid is 1.5mm-1.75mm.

[0009] As a preferred solution of the present invention, the specific steps of fitting in S2 are to calculate the change rate of the pixel points of the weld contour in the image data by derivation, determine the approximate position of the weld, fit the weld area image data by the least squares method and then fit the interference points with large discrete values, and after fitting again, the data point closest to the intersection of the contour lines is the edge contour of the weld, and according to the coordinates of the edge contour feature points, the surface contour geometric dimensions of the weld at that location are solved to obtain the surface contour image.

[0010] As a preferred solution of the present invention, the specific steps of performing three-dimensional reconstruction in S2 are: converting the surface contour image pixel data into three-dimensional point cloud data through the internal and external parameter matrix of the industrial camera and the light plane equation, setting the distance threshold σ, traversing all the points in the point cloud data, and when the point cloud data has a distance greater than the distance threshold σ, filtering out the abnormal noise point, fitting the data points within a certain range on the diagonal and rows and columns where the abnormal point is located through a high-order spline curve, interpolating the Z value according to the X and Y values, correcting the abnormal point cloud noise, and using median filtering to smooth the points to obtain three-dimensional point cloud data.

[0011] As a preferred solution of the present invention, the specific method for evaluating the quality of the weld is to establish an ideal weld model, place the three-dimensional point cloud data and the ideal weld contour point cloud in the same coordinate system, calculate the accuracy difference between the three-dimensional point cloud data and the ideal weld contour point cloud, and compare the difference with the standard threshold. If the difference is higher than the standard threshold, the weld at the standard point has quality defects, and the point is marked in the three-dimensional point cloud data. According to the position of the point in the three-dimensional point cloud data, the coordinates of the point in the surface contour image are determined and marked.

[0012] As a preferred solution of the present invention, the welding current during welding in S1 is 220A-270A, the voltage of the welding gun is 22V-30V, the moving speed of the welding gun is 20cm / min-30cm / min, the welding temperature is 120℃-150℃, and carbon dioxide gas is sprayed on the welding surface to form a protective cover during welding. The carbon dioxide gas flow rate is 18L / min-24L / min, and the carbon dioxide gas is sprayed obliquely. The welding wire of the welding gun is a Φ1.5mm flux-cored welding wire.

[0013] Compared with the prior art, the present invention has the following beneficial effects: 1. In the present invention, the welding position and the surrounding parts of the cold-bent steel are cleaned. After cleaning, the welding position is preheated by low-voltage and high-current resistance heating. After the preheating is completed, flux is applied to the welding position, and a welding gun is used to perform welding operation on the welding position. The weld image is continuously collected by an industrial camera, and the image data is fitted to obtain the surface contour image of the weld area. The surface contour image is three-dimensionally reconstructed to obtain the three-dimensional point cloud data of the weld area. Based on the three-dimensional point cloud data, the weld quality is evaluated, and the unqualified welds are repaired according to the evaluation results, and the secondary welds are evaluated. The above operation is repeated until the weld quality meets the standard and the welding is completed. Finally, the welding slag near the welding part of the cold-formed steel is removed and the welded cold-formed steel is insulated. After the insulation is completed, the temperature is lowered to room temperature to obtain the welded cold-formed steel. A welding alloy solution with a specific composition is coated on the welding area to prevent the appearance of brittle intermetallic compounds in the weld nugget, reduce the porosity of the weld, and improve the welding performance, thereby improving the weld strength. At the same time, the weld quality is detected by using structured light imaging technology to evaluate the welding quality. After welding, the stress of the welding part is released by the method of insulation and slow cooling, and the load-bearing capacity of the welding part is improved, which solves the problem of poor welding effect and inability to evaluate the welding quality during the existing cold-formed steel welding. DETAILED DESCRIPTION

[0014] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0015] To facilitate understanding of the present invention, the present invention will be described more comprehensively below and several embodiments of the present invention are given. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present invention more thorough and comprehensive.

[0016] It should be noted that when an element is referred to as being "fixed on" another element, it may be directly on the other element or there may also be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may also be a central element. The terms "vertical", "horizontal", "left", "right" and similar expressions used in this article are for illustrative purposes only.

[0017] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which the present invention belongs. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0018] Embodiment, the present invention provides a technical solution: A cold-bent steel forming and welding method comprises the following steps: S1, clean the welding position and nearby parts of the cold-bent steel. After cleaning, preheat the welding position by low voltage and high current resistance heating. After the preheating treatment, apply flux to the welding position and use a welding gun to perform welding operations on the welding position; S2, continuously collecting weld images through an industrial camera, fitting the image data to obtain a surface profile image of the weld area, performing three-dimensional reconstruction on the surface profile image to obtain three-dimensional point cloud data of the weld area, evaluating the weld quality based on the three-dimensional point cloud data, performing repair welding on unqualified welds based on the evaluation results, and evaluating the secondary welds, and repeating the above operations until the weld quality meets the standard; S3, after welding is completed, remove the welding slag near the welding part of the cold-bent steel and keep the welded cold-bent steel at a temperature of 100℃-120℃ for 1h-2h. After the insulation is completed, cool it to room temperature at a rate of 2℃ / min-3℃ / min to obtain the welded cold-bent steel.

[0019] Furthermore, the cleaning method of the welding position in S1 is to use sandpaper or a grinding wheel to grind the welding part of the cold-bent steel to remove the oxide film, use a mixture of 1.2 mol / L dilute hydrochloric acid and 1 mol / L dilute nitric acid in a volume ratio of 1:1.5 to prepare a cleaning solution, use the cleaning solution to clean the welding part of the cold-bent steel, and after cleaning, rinse with acetone and deionized water for 3-4 times in turn.

[0020] Furthermore, the specific steps of the preheating treatment in S1 are to heat the welding area of ​​the cold-bent steel to 150°C-180°C by low voltage and high current resistance heating, the preheating current is 4.65kA-4.8kA, and the heating time is 5min-6min. After the heating is completed, the welding area of ​​the cold-bent steel is cooled to reduce its temperature to 100°C-120°C, and the welding area of ​​the cold-bent steel is heated again to quickly rise to 170°C-190°C within 0.75s-1.75s, and then the welding alloy liquid is applied to the welding area of ​​the left cold-bent steel.

[0021] Furthermore, the welding alloy liquid is prepared by mixing niobium metal powder, nickel metal powder, copper metal powder and acetone solvent in a mass ratio of 1:60:110:300, the viscosity of the welding alloy liquid is 0.88Pa·s-0.95Pa·s, and the coating thickness of the welding alloy liquid is 1.5mm-1.75mm.

[0022] Furthermore, the specific steps of fitting in S2 are to calculate the change rate of the pixel points of the weld contour in the image data by derivation, determine the approximate position of the weld, fit the weld area image data by the least squares method, and then use the cubic spline curve to fit the weld area image data, remove interference points with large discrete values, and after fitting again, the data point closest to the intersection of the contour lines is the edge contour of the weld. According to the coordinates of the edge contour feature points, the surface contour geometric dimensions of the weld at that location are solved to obtain the surface contour image.

[0023] Furthermore, the specific steps of performing three-dimensional reconstruction in S2 are: converting the surface contour image pixel data into three-dimensional point cloud data through the internal and external parameter matrix of the industrial camera and the light plane equation, setting the distance threshold σ, traversing all the points in the point cloud data, and when the point cloud data has a point greater than the distance threshold σ, filtering out the abnormal noise point, fitting the data points within a certain range on the diagonal and rows and columns where the abnormal point is located through a high-order spline curve, interpolating the Z value according to the X and Y values, correcting the abnormal point cloud noise, and using the median filter to smooth the points to obtain the three-dimensional point cloud data.

[0024] Furthermore, the specific method for evaluating the weld quality is to establish an ideal weld model, place the three-dimensional point cloud data and the ideal weld contour point cloud in the same coordinate system, calculate the accuracy difference between the three-dimensional point cloud data and the ideal weld contour point cloud, and compare the difference with the standard threshold. If the difference is higher than the standard threshold, the weld at the standard point has quality defects, and the point is marked in the three-dimensional point cloud data. According to the position of the point in the three-dimensional point cloud data, the coordinates of the point in the surface contour image are determined and marked.

[0025] Furthermore, the welding current during welding in S1 is 220A-270A, the voltage of the welding gun is 22V-30V, the moving speed of the welding gun is 20cm / min-30cm / min, the welding temperature is 120℃-150℃, and carbon dioxide gas is sprayed on the welding surface to form a protective cover during welding. The carbon dioxide gas flow rate is 18L / min-24L / min, and the carbon dioxide gas is sprayed obliquely. The welding wire of the welding gun is a Φ1.5mm flux-cored welding wire.

[0026] Use sandpaper or grinding wheel to grind the welding parts of cold-formed steel to remove the oxide film, use 1.2 mol / L dilute hydrochloric acid and 1 mol / L dilute nitric acid in a volume ratio of 1:1.5 to make a cleaning solution, use the cleaning solution to clean the welding parts of cold-formed steel, and after cleaning, rinse with acetone and deionized water three times in sequence; After cleaning, the welding area of ​​the cold-formed steel is heated to 150°C by low-voltage and high-current resistance heating, the preheating current is 4.65kA, and the heating time is 5min. After the heating is completed, the welding area of ​​the cold-formed steel is cooled to reduce its temperature to 100°C, and the welding area of ​​the cold-formed steel is heated again to rapidly increase the temperature to 170°C within 1.75s. Niobium metal powder, nickel metal powder, copper metal powder and acetone solvent are mixed in a mass ratio of 1:60:110:300 to obtain a welding alloy liquid with a viscosity of 0.88Pa·s, and then the welding alloy liquid is applied to the welding area of ​​the cold-formed steel, and the coating thickness of the welding alloy liquid is 1.5mm; After the preheating treatment, flux is applied to the welding position, and a welding gun is used to perform welding operations on the welding position. The welding current during welding is 220A, the voltage of the welding gun is 22V, the moving speed of the welding gun is 20cm / min, the welding temperature is 120°C, and carbon dioxide gas is sprayed on the welding surface to form a protective cover during welding. The carbon dioxide gas flow rate is 18L / min, and the carbon dioxide gas is sprayed obliquely. The welding wire of the welding gun is a Φ1.5mm flux-cored welding wire; The weld images are continuously collected by industrial cameras, and the pixel change rate of the weld contour in the image data is calculated by derivation. After the approximate position of the weld is determined, the least squares method is used for fitting, and then the cubic spline curve is used to fit the weld area image data, and the interference points with large discrete values ​​are eliminated. After fitting again, the data point closest to the intersection of the contour line is the edge contour of the weld. According to the coordinates of the edge contour feature points, the geometric dimensions of the surface contour of the weld at this location are solved to obtain the surface contour image; Through the internal and external parameter matrix of the industrial camera and the light plane equation, the surface profile image pixel data is converted into three-dimensional point cloud data. The distance threshold σ is set, and all points in the point cloud data are traversed. When the point in the point cloud data is greater than the distance threshold σ, the abnormal noise point is filtered out, and the data points within a certain range on the diagonal and rows and columns where the abnormal point is located are fitted by a high-order spline curve. The Z value is interpolated according to the X and Y values, the abnormal point cloud noise is corrected, and the median filter is used to smooth the points to obtain the three-dimensional point cloud data; Establish an ideal weld model, place the 3D point cloud data and the ideal weld contour point cloud in the same coordinate system, calculate the accuracy difference between the 3D point cloud data and the ideal weld contour point cloud, and compare the difference with the standard threshold. If the difference is higher than the standard threshold, the weld at the point has quality defects, and the point is marked in the 3D point cloud data. According to the position of the point in the 3D point cloud data, the coordinates of the point in the surface contour image are determined and marked. According to the evaluation results, the unqualified welds are repaired and the secondary welds are evaluated. Repeat the above operations until the weld quality meets the standard; After welding is completed, the welding slag near the welding part of the cold-formed steel is removed and the welded cold-formed steel is kept at 100°C for 1 hour. After the insulation is completed, the temperature is lowered to room temperature at a rate of 2°C / min to obtain the welded cold-formed steel.

[0027] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A cold-bent steel forming and welding method, characterized in that: The following steps are involved: S1, clean the welding position and nearby parts of the cold-bent steel. After cleaning, preheat the welding position by low voltage and high current resistance heating. After the preheating treatment, apply flux to the welding position and use a welding gun to perform welding operations on the welding position; S2, continuously collecting weld images through an industrial camera, fitting the image data to obtain a surface profile image of the weld area, performing three-dimensional reconstruction on the surface profile image to obtain three-dimensional point cloud data of the weld area, evaluating the weld quality based on the three-dimensional point cloud data, performing repair welding on unqualified welds based on the evaluation results, and evaluating the secondary welds, and repeating the above operations until the weld quality meets the standard; S3, after welding is completed, remove the welding slag near the welding part of the cold-bent steel and keep the welded cold-bent steel at a temperature of 100℃-120℃ for 1h-2h. After the insulation is completed, cool it to room temperature at a rate of 2℃ / min-3℃ / min to obtain the welded cold-bent steel.

2. A cold-bent steel forming and welding method according to claim 1, characterized in that: The cleaning method of the welding position in S1 is to use sandpaper or a grinding wheel to grind the welding part of the cold-bent steel to remove the oxide film, use a mixture of 1.2 mol / L dilute hydrochloric acid and 1 mol / L dilute nitric acid in a volume ratio of 1:1.5 to prepare a cleaning solution, use the cleaning solution to clean the welding part of the cold-bent steel, and after cleaning, rinse with acetone and deionized water for 3-4 times in turn.

3. A cold-bent steel forming and welding method according to claim 1, characterized in that: The specific steps of the preheating treatment in S1 are to heat the welding area of ​​the cold-bent steel to 150°C-180°C by low voltage and high current resistance heating, the preheating current is 4.65kA-4.8kA, and the heating time is 5min-6min. After the heating is completed, the welding area of ​​the cold-bent steel is cooled to reduce its temperature to 100°C-120°C, and the welding area of ​​the cold-bent steel is heated again to rapidly increase the temperature to 170°C-190°C within 0.75s-1.75s, and then the welding alloy liquid is applied to the welding area of ​​the left cold-bent steel.

4. A cold-bent steel forming and welding method according to claim 3, characterized in that: The welding alloy liquid is prepared by mixing niobium metal powder, nickel metal powder, copper metal powder and acetone solvent in a mass ratio of 1:60:110:

300. The viscosity of the welding alloy liquid is 0.88Pa·s-0.95Pa·s, and the coating thickness of the welding alloy liquid is 1.5mm-1.75mm.

5. The cold-bent steel forming and welding method according to claim 1, characterized in that: The specific steps of fitting in S2 are: calculating the change rate of the weld contour pixel points in the image data by derivation, determining the approximate position of the weld, fitting the weld area image data by the least squares method, and then fitting the weld area image data by the cubic spline curve, eliminating the interference points with large discrete values, and fitting again. The data point closest to the intersection of the contour lines is the edge contour of the weld. According to the coordinates of the edge contour feature points, the geometric dimensions of the surface contour of the weld at that location are solved to obtain the surface contour image.

6. A cold-bent steel forming and welding method according to claim 1, characterized in that: The specific steps of performing three-dimensional reconstruction in S2 are: converting the surface profile image pixel data into three-dimensional point cloud data through the internal and external parameter matrix of the industrial camera and the light plane equation, setting the distance threshold σ, traversing all the points in the point cloud data, and filtering out the abnormal noise points when the distance of the points in the point cloud data is greater than the distance threshold σ, fitting the data points within a certain range on the diagonal and rows and columns where the abnormal points are located through high-order spline curves, interpolating the Z value according to the X and Y values, correcting the abnormal point cloud noise points, and using median filtering to smooth the points to obtain three-dimensional point cloud data.

7. A cold-bent steel forming and welding method according to claim 1, characterized in that: The specific method for evaluating the quality of the weld is to establish an ideal weld model, place the three-dimensional point cloud data and the ideal weld contour point cloud in the same coordinate system, calculate the accuracy difference between the three-dimensional point cloud data and the ideal weld contour point cloud, and compare the difference with the standard threshold. If the difference is higher than the standard threshold, the weld at the point has quality defects, and the point is marked in the three-dimensional point cloud data. According to the position of the point in the three-dimensional point cloud data, the coordinates of the point in the surface contour image are determined and marked.

8. The cold-bent steel forming and welding method according to claim 1, characterized in that: The welding current during welding in S1 is 220A-270A, the voltage of the welding gun is 22V-30V, the moving speed of the welding gun is 20cm / min-30cm / min, the welding temperature is 120℃-150℃, and carbon dioxide gas is sprayed on the welding surface to form a protective cover during welding. The carbon dioxide gas flow rate is 18L / min-24L / min, and the carbon dioxide gas is sprayed obliquely. The welding wire of the welding gun is a Φ1.5mm flux-cored welding wire.