A method for controlling welding gun trajectory in automated fillet weld welding

Abstract

The present invention is a method for controlling the welding gun track in automated fillet welding. From the start of welding, the welding machine acquires and records the welding current of the welding gun at the end position 1 of the welding gun track, the end position 2 of the welding gun track and the center position of the welding gun track in real time; at the end of the set time window, the accumulated current value is divided by the total number of times the real-time current is acquired within the set time window, and the instantaneous average welding current at the three positions at the end of the set time window is obtained and recorded; the instantaneous average welding current difference 1 and the instantaneous welding current difference 2 are calculated; when the instantaneous average welding current difference 1 is greater than the preset value 1 and the instantaneous welding current difference 2 is greater than the preset value 2, the welding gun position is adjusted; and the steps are repeated until the fillet welding is completed. The present invention is adapted to the welding seam conditions and improves the welding quality; the weld alignment is automatically adjusted to improve the welding efficiency, the weight and size of the system equipment are not increased, the automated welding control is facilitated, and the welding environment has little influence.

Description

Technical Field

[0001] The invention relates to the technical field of automated welding, and in particular to a method for controlling a welding gun trajectory in automated fillet welding. Background Art

[0002] The sealing welds of the water-cooled wall of the boiler in a thermal power plant are fillet welds, which have the characteristics of a large number of welds, a large welding workload, and a long labor time. Excellent heating surface sealing welding quality is an important guarantee for the safe and economical operation of the boiler and the control of environmental pollution of the unit. At present, the working environment of on-site welding construction is very harsh. Traditional manual welding is very harmful to the human body. With the continuous compression of the construction period, there is a high demand for how to complete the welding work efficiently and with high quality. Automated welding can improve work efficiency, ensure welding quality, and reduce the need for labor protection, and has broad application prospects.

[0003] However, the welding position of fillet welds is complex, and the size of workpieces on site is irregular. The automatic welding machine needs to control and adjust the welding trajectory in real time according to the changes of the workpiece during automatic welding. Existing weld tracking technology uses photoelectric equipment, such as cameras or laser equipment, to track welds, but photoelectric equipment is expensive and is subject to many restrictions on site conditions. For example, its accuracy decreases in dark and dusty environments. Summary of the invention

[0004] The present invention aims to solve the deficiencies of the prior art and provide a method for controlling the welding gun trajectory in automated fillet welding. With the rapid development of digital technology, digital welding machines can read real-time welding current and other parameters at a high frequency, and computing chips can quickly process the acquired welding machine current. These new technical means are conducive to solving the welding trajectory control problem.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for controlling the trajectory of a welding gun in automated fillet welding, comprising the following steps:

[0007] S1. From the start of welding, the welding machine acquires and records the welding current of the welding gun at the end position 1 of the welding gun track, the end position 2 of the welding gun track and the center position of the welding gun track in real time;

[0008] S2. Accumulate the welding current at the first end position of the welding gun track, the second end position of the welding gun track and the center position of the welding gun track respectively within the set time window; and at the end of the set time window, divide the accumulated current value by the total number of times the real-time current is obtained within the set time window, and obtain and record the real-time average welding current at the three positions at the end of the set time window;

[0009] S3. After welding is started and the first set time window ends, each time the welding gun passes through the first end position of the welding gun trajectory, the second end position of the welding gun trajectory and the center position of the welding gun trajectory, the instantaneous average welding current of the welding gun at the first end position of the trajectory obtained in step S2 is subtracted from the instantaneous average welding current of the welding gun at the second end position of the trajectory, and the absolute value of the obtained difference is recorded as the instantaneous average welding current difference one; the real-time welding current obtained by the welding gun at the center position of the trajectory is subtracted from the instantaneous average welding current of the welding gun at the center position of the trajectory obtained in step S2, and the absolute value of the obtained difference is recorded as the instantaneous welding current difference two;

[0010] S4, if the instantaneous average welding current difference 1 calculated in step S3 is greater than the preset value 1, and the instantaneous welding current difference 2 calculated in step S3 is greater than the preset value 2, then adjust the welding gun to move a specified distance to the end point with the smaller instantaneous average welding current between the welding gun trajectory end point position 1 and the welding gun trajectory end point position 2;

[0011] S5. Repeat the operations in steps S1-S4 until the fillet weld is completed.

[0012] In step S1, the welding machine is a digital welding machine. Every time the welding gun swings to the end position 1 of the welding gun trajectory, the end position 2 of the welding gun trajectory and the center position of the welding gun trajectory, the welding current at each location is obtained in real time by the digital welding machine.

[0013] In step S2, the time window is set to be no less than three seconds and no more than ten seconds.

[0014] In step S4, the preset value one is not less than ten amperes and not more than fifty amperes.

[0015] In step S4, the preset value 2 is not less than ten amperes and not greater than fifty amperes.

[0016] In step S4, the designated distance of movement of the welding gun is adjusted to be no greater than one millimeter.

[0017] The welding gun oscillates at a frequency of five times per second, and the welding wire used by the welding gun is ER70-S6 with a diameter of 1.2 mm.

[0018] The beneficial effects of the present invention are as follows: the present invention adapts to the weld conditions and improves the welding quality; automatically adjusts the weld alignment and improves the welding efficiency, does not increase the weight and size of the system equipment, facilitates automated welding control, and is less affected by the welding environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of a specific embodiment 1 of the present invention;

[0020] Figure 2 It is a schematic diagram of specific embodiment 2 of the present invention;

[0021] Figure 3 It is a flow chart of the present invention;

[0022] In the figure: 1- welding gun; 2- welding wire; 3- welding gun track end point position 1; 4- welding gun track end point position 2; 5- welding gun track center position; 6- 20# carbon steel workpiece 1; 7- 20# carbon steel workpiece 2; 8- 20# carbon steel workpiece 3; 9- 20# carbon steel workpiece 4;

[0023] The following is a detailed description of the embodiments of the present invention with reference to the accompanying drawings. DETAILED DESCRIPTION

[0024] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention. The present invention is described in more detail by way of example with reference to the accompanying drawings in the following paragraphs. The advantages and features of the present invention will become clearer according to the following description and claims. It should be noted that the drawings are all in a very simplified form and are not in precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0025] It should be noted that when a component is referred to as being "fixed to" another component, it may be directly on the other component or there may also be a component centered. When a component is considered to be "connected to" another component, it may be directly connected to the other component or there may also be a component centered. When a component is considered to be "set on" another component, it may be directly set on the other component or there may also be a component centered. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein 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.

[0027] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0028] A method for controlling the trajectory of a welding gun in automated fillet welding, comprising the following steps:

[0029] S1. From the start of welding, the welding machine acquires and records the welding current of the welding gun 1 at the end position 1 3 of the welding gun track, the end position 2 4 of the welding gun track and the center position 5 of the welding gun track in real time;

[0030] S2. Accumulate the welding current at the welding gun track end position 1 3, the welding gun track end position 2 4 and the welding gun track center position 5 respectively within the set time window; the set time window is not less than three seconds and not more than ten seconds, and at the end of the set time window, divide the accumulated current value by the total number of times the real-time current is obtained within the set time window, and obtain and record the real-time average welding current at the three positions at the end of the set time window;

[0031] S3. After welding is started and the first set time window ends, each time the welding gun 1 passes through the welding gun track endpoint position 1 3, the welding gun track endpoint position 2 4 and the welding gun track center position 5, the instantaneous average welding current of the welding gun 1 at the track endpoint position 1 3 obtained in step S2 is subtracted from the instantaneous average welding current of the welding gun 1 at the track endpoint position 2 4, and the obtained difference is recorded as the instantaneous average welding current difference 1 after taking the absolute value; the real-time welding current obtained by the welding gun 1 at the track center position 5 is subtracted from the instantaneous average welding current of the welding gun 1 at the track center position 5 obtained in step S2, and the obtained difference is recorded as the instantaneous welding current difference 2 after taking the absolute value;

[0032] S4, if the instantaneous average welding current difference 1 calculated in step S3 is greater than the preset value 1, the preset value 1 is not less than ten amperes and not more than fifty amperes, and the instantaneous welding current difference 2 calculated in step S3 is greater than the preset value 2, the preset value 2 is not less than ten amperes and not more than fifty amperes, then adjust the welding gun 1 to move the specified distance to the end point with the smaller instantaneous average welding current between the welding gun trajectory end point position 1 3 and the welding gun trajectory end point position 2 4; the specified distance is not more than one millimeter;

[0033] S5. Repeat the operations in steps S1-S4 until the fillet weld is completed.

[0034] In step S1, the welding machine is a digital welding machine. Every time the welding gun 1 swings to the welding gun track end position 1 3, the welding gun track end position 2 4 and the welding gun track center position 5, the welding current at each location is obtained in real time by the digital welding machine.

[0035] The working principle of the present invention is as follows:

[0036] In fillet welding, a swinging method is usually used to melt and connect the metals of the workpieces on both sides. In the swinging motion of fillet welding, the distance between the welding wire 2 and the workpiece is constantly changing. In ideal fillet welding, when the welding wire 2 is aligned with the center of the fillet weld, the distance between the welding wire 2 and the workpiece is the largest; when the welding wire 2 reaches both ends of the swing, the distance between the welding wire 2 and the workpiece is the shortest. For metal arc welding (MAG) and MIG, the welding characteristics are constant voltage mode, that is, the welding voltage remains constant, and the welding current changes with the distance between the welding wire 2 and the workpiece: when the welding wire 2 is close to the workpiece, the welding current increases; when the welding wire 2 is far from the workpiece, the welding current decreases. Therefore, when the fillet welding is performed normally, the real-time welding current is the largest when the welding gun 1 swings to both ends, and the difference between the two welding currents is not large; when the welding gun 1 is facing the center of the fillet weld, that is, at the swing center of the welding gun 1, the real-time welding current is the smallest. When the welding gun 1 deviates from the center of the fillet weld during welding, the difference in the real-time welding current at the two ends of the swing becomes larger, and the real-time welding current at the swing center will increase accordingly. According to the calculation and comparison of the real-time welding current at a specific position and the instant average welding current, it can be judged whether the welding deviates from the fillet welding requirements. In order to reduce the influence of welding current fluctuations, the present invention averages the real-time welding currents obtained within a short time window, such as three to ten seconds, and then uses their respective average values ​​for calculation and comparison, and judges whether the welding trajectory deviates from the fillet welding position based on the calculation and comparison results, and further judges whether the welding gun position needs to be adjusted, so as to control the welding gun trajectory to meet the requirements. Specific embodiment 1:

[0038] refer to Figure 1 and Figure 3 , using automated MIG welding to weld fillet welds of 20# carbon steel workpiece 1 6 and 20# carbon steel workpiece 2 7: welding wire 2 is made of ER70-S6 with a diameter of 1.2 mm. By reading the real-time welding current of welding gun 1 when it swings to the end position 1 3 of the welding gun track, the end position 2 4 of the welding gun track and the center position 5 of the welding gun track during automated welding, calculation and comparison are performed to determine whether the movement of welding gun 1 deviates from the fillet welding position and control the welding track of welding gun 1.

[0039] The time window for reading the real-time welding current is set to three seconds, the preset value 1 and the preset value 2 are set to 10 amperes, and the swing frequency of welding gun 1 is set to five times per second.

[0040] The digital welding machine reads and records in real time the welding current at position 13 of the end point of the welding gun trajectory when the welding gun 1 swings to a position 16 toward the workpiece, the welding current at position 24 of the end point of the welding gun trajectory when the welding gun 1 swings to a position 27 toward the workpiece, and the welding current at position 5 of the center of the welding gun trajectory when the welding gun 1 swings to the center.

[0041] Within three seconds after the start of welding, only the welding current is read and calculated, and the position of the welding gun 1 is not determined and controlled and adjusted.

[0042] At the end of the first time window, that is, three seconds after the start of welding, all real-time welding currents recorded by welding gun 1 at the end position 3 of the welding gun trajectory corresponding to workpiece 1 6 in the previous three seconds are averaged, and the instantaneous average welding current value at this position is 202A; all real-time currents recorded by welding gun 1 at the end position 24 of the welding gun trajectory corresponding to workpiece 2 7 in the previous three seconds are averaged, and the instantaneous average welding current value at this position is 205A; all real-time welding currents recorded by welding gun 1 at the center position, that is, the center position 5 of the welding gun trajectory in the previous three seconds are averaged, and the instantaneous average welding current value at this position is 192A, and the real-time current value at this position is 190A.

[0043] At the end of the first time window, that is, three seconds after the start of welding, the real-time welding current and the average welding current at the welding gun 1 position are compared and calculated to determine:

[0044] The instantaneous average welding current of welding gun 1 at the trajectory endpoint position 1 3 is subtracted from the instantaneous average welding current of welding gun 1 at the trajectory endpoint position 2 4. The absolute value of the difference is three amperes, which is recorded as the instantaneous average welding current difference one;

[0045] The real-time welding current of welding gun 1 at position 5 of the welding gun track center minus the instantaneous average welding current at position 5 of the welding gun track center, the absolute value of the difference is two amperes, and is recorded as the instantaneous welding current difference two;

[0046] When the instant average welding current difference one value is three amperes, which is less than the preset value one, and the instant welding current difference two value is two amperes, which is less than the preset value two, it is determined that the position of the welding gun 1 is appropriate and the welding gun 1 does not need to be adjusted.

[0047] The trajectory calculation and judgment of the welding gun 1 is controlled and performed continuously during the welding process until the welding is completed.

[0048] Embodiment 2:

[0049] refer to Figure 2 and Figure 3 , using automated MIG welding to weld fillet seams of 20# carbon steel workpiece 3 8 and 20# carbon steel workpiece 4 9: the material of welding wire 2 is ER70-S6, with a diameter of 1.2 mm. By reading the real-time welding current when welding gun 1 swings to welding gun track end position 1 3, welding gun track end position 2 4 and welding gun track center position 5 during automated welding, calculation and comparison are performed to determine whether the movement of welding gun 1 deviates from the fillet welding position and control the track of welding gun 1.

[0050] The time window for reading the real-time welding current is set to three seconds, the preset value 1 and the preset value 2 are set to 10 amperes, and the swing frequency of welding gun 1 is set to five times per second.

[0051] The digital welding machine reads and records in real time the welding current at the end position 13 of the welding gun trajectory when the welding gun 1 swings to the workpiece 38, the welding current at the end position 24 of the welding gun trajectory when the welding gun 1 swings to the workpiece 49, and the welding current when the welding gun 1 swings to the center position 5 of the welding gun trajectory.

[0052] Three seconds after the start of welding, the position of the welding gun 1 is judged and controlled and adjusted.

[0053] When 200 seconds of welding is completed, the instant average welding current value obtained by averaging all real-time welding currents recorded when the welding gun 1 swings to the workpiece 3 8 within the previous three seconds is 218A; the instant average welding current value obtained by averaging all real-time welding currents recorded when the welding gun 1 swings to the workpiece 4 9 within the previous three seconds is 195A; the instant average welding current value obtained by averaging all real-time welding currents recorded when the welding gun 1 swings to the center position 5 of the welding gun trajectory within the previous three seconds is 190A, and the actual real-time welding current value is 205A.

[0054] When the welding is completed for 200 seconds, the position of welding gun 1 is judged. The first judged instant average welding current difference one value is 13 amperes, which is greater than 10 amperes, and the instant welding current difference two value is 15 amperes, which is greater than 10 amperes. It is determined that welding gun 1 deviates from the fillet weld. The welding gun 1 is adjusted and moved by 0.2 mm toward the direction of workpiece 49 through the automated welding machine.

[0055] The trajectory calculation and judgment control of the welding gun 1 are continuously performed during the welding process until the welding is completed.

[0056] The present invention adapts to the welding seam conditions and improves the welding quality; automatically adjusts the welding seam alignment and improves the welding efficiency; does not increase the weight and size of the system equipment, is convenient for automatic welding control, and is less affected by the welding environment.

[0057] The present invention is described above by way of example in conjunction with the accompanying drawings. It is obvious that the specific implementation of the present invention is not limited to the above-mentioned method. As long as various improvements are made using the method concept and technical solution of the present invention, or are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A method for controlling the trajectory of a welding gun in automated fillet welding, characterized in that: The specific steps are: S1. From the start of welding, the welding machine acquires and records in real time the welding current of the welding gun (1) at the end position 1 (3) of the welding gun track, the end position 2 (4) of the welding gun track and the center position (5) of the welding gun track; S2, accumulating the welding current at the end point position 1 (3), the end point position 2 (4) and the center position (5) of the welding gun trajectory within a set time window; and at the end of the set time window, dividing the accumulated current value by the total number of times the real-time current is obtained within the set time window, to obtain and record the real-time average welding current at the three positions at the end of the set time window; S3. After welding is started and the first set time window ends, each time the welding gun (1) passes through the welding gun track endpoint position 1 (3), the welding gun track endpoint position 2 (4) and the welding gun track center position (5), the instantaneous average welding current of the welding gun (1) at the track endpoint position 1 (3) obtained in step S2 is subtracted from the instantaneous average welding current of the welding gun (1) at the track endpoint position 2 (4), and the absolute value of the difference is recorded as the instantaneous average welding current difference 1; the real-time welding current obtained by the welding gun (1) at the track center position (5) is subtracted from the instantaneous average welding current of the welding gun (1) at the track center position (5) obtained in step S2, and the absolute value of the difference is recorded as the instantaneous welding current difference 2; S4. If the instantaneous average welding current difference 1 calculated in step S3 is greater than the preset value 1, and the instantaneous welding current difference 2 calculated in step S3 is greater than the preset value 2, then the welding gun (1) is adjusted to move a specified distance toward the end point of the welding gun trajectory endpoint position 1 (3) and the welding gun trajectory endpoint position 2 (4) where the instantaneous average welding current is smaller; S5. Repeat the operations in steps S1-S4 until the fillet weld is completed.

2. A method for controlling the trajectory of a welding gun in automated fillet welding according to claim 1, characterized in that: In step S1, the welding machine is a digital welding machine, and each time the welding gun (1) swings to the end position 1 (3) of the welding gun trajectory, the end position 2 (4) of the welding gun trajectory and the center position (5) of the welding gun trajectory, the welding current at each location is obtained in real time by the digital welding machine.

3. A method for controlling the trajectory of a welding gun in automated fillet welding according to claim 2, characterized in that: In step S2, the time window is set to be no less than three seconds and no more than ten seconds.

4. A method for controlling the trajectory of a welding gun in automated fillet welding according to claim 3, characterized in that: In step S4, the preset value one is not less than ten amperes and not more than fifty amperes.

5. A method for controlling the trajectory of a welding gun in automated fillet welding according to claim 4, characterized in that: In step S4, the preset value 2 is not less than ten amperes and not greater than fifty amperes.

6. A method for controlling the trajectory of a welding gun in automated fillet welding according to claim 5, characterized in that: In step S4, the designated distance that the welding gun (1) moves is adjusted to be no greater than one millimeter.

7. A method for controlling the trajectory of a welding gun in automated fillet welding according to claim 6, characterized in that: The welding gun (1) has an oscillation frequency of five times per second, and the material of the welding wire (2) used for welding the welding gun (1) is ER70-S6 with a diameter of 1.2 mm.

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