Gas shielded welding model-free dry extension length control method

Abstract

The application discloses a model-free dry extension length control method for gas shielded welding. The method is characterized in that the real-time welding current corresponding to the dry extension adjustment in the all-position welding process is manually adjusted, a segmented linear regression method is used to establish the parameter relationship in different positions, and the dry extension length control range is indirectly obtained, so that the dry extension height is controlled by the current size. The technical scheme of the application avoids the model control adaptability problem under the complex welding condition, uses the result-oriented method, indirectly solves the automatic control problem of the dry extension length adjustment, and is more suitable for the dry extension control adaptability of the all-position welding system. The method liberates the manual intervention in the welding process and realizes the partial intelligent work. The method has strong adaptability, convenient control and guaranteed precision.

Description

Technical Field

[0001] This invention belongs to the field of GMAW welding automatic control technology, and more specifically, it relates to a method for controlling the extension length during the welding process. Under the welding conditions of long-distance pipelines, this method can achieve real-time automatic control of the extension length. Background Technology

[0002] With the widespread application of automated pipeline welding technology, the degree of automation in automated welding determines the weld formation and pass rate. To address the rising labor costs and the gradual phasing out of automated welding equipment that relies on manual experience, various weld tracking methods have emerged, including contact and non-contact methods, as automation and intelligent technologies mature. Arc tracking, active vision, and passive vision tracking methods are widely used in the welding industry. Arc tracking uses real-time acquired current, voltage, and other direct electrical signals to establish a mathematical model based on the inherent characteristics of the arc to control the arc extension length. However, the model's adaptability and application conditions are limited under complex welding processes. Active vision and passive vision can indirectly control the arc length by measuring the distance between the welding torch and the workpiece. However, the acquisition, filtering, noise reduction, sparsity extraction, and fitting of image signals require extensive algorithmic analysis, while also considering the protection of the light source and imaging system under various complex environments. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a model-free method for controlling the extension length of gas shielded welding. By extracting the welding current, establishing a regression equation, and comparing the current parameters at different positions as benchmark values ​​with the current collected during the automatic welding process, the method aims to control the extension length range.

[0004] The technical objective of this invention is achieved through the following technical solution.

[0005] A method for controlling the stick-out length of gas shielded welding without a mold includes:

[0006] A welding power source that automatically matches the corresponding welding voltage and current at a given wire feed speed is used. By measuring the welding current at different welding speeds, polynomial fitting is performed using MATLAB, and the curve fitting data (i.e., the linear equation of wire feed speed versus welding current) is read. The welding current corresponding to the input wire feed speed is automatically calculated using the linear fitting formula of the programming system and denoted as current a.

[0007] In the process of automatic welding of pipe cross sections in all positions, the extension length of the welding torch is indirectly controlled by adjusting the height of the welding torch. According to the welding process standard requirements, the welding in all positions is completed within the set wire feeding speed range. The current compensation value b in all positions is obtained, and the relationship between different welding positions and current compensation values ​​is established.

[0008] During the all-position automatic welding process of the pipe section, the wire feeding speed setpoints at different positions are called in real time. The corresponding welding current and current compensation value are calculated by the linear equation of wire feeding speed and welding current (i.e., the current compensation value at different positions is obtained by position sensing). The sum of the two is used as the current reference value at that position. The real-time value and the reference value are compared to determine the difference in current magnitude. The upper and lower positions of the welding torch are adjusted according to the set adjustment threshold, thereby adjusting the extension length.

[0009] In the above technical solution, the welding current is collected by a current sensor. The corresponding current is calculated by curve fitting based on the wire feed speed setting.

[0010] In the above technical solution, the vertical position adjustment of the welding torch is achieved through an actuator.

[0011] In the above technical solution, the position information of the welding torch is obtained by using an angle sensor.

[0012] In the above technical solution, the acquisition card converts the welding current signal into a digital signal and transmits it to the computing unit.

[0013] In the above technical solution, the computing unit calls the current compensation value according to the real-time welding angle at all positions, and adds the welding current to the current compensation value to obtain the current reference value at that position. That is, the current reference value at the current position is obtained by adding the curve-fitted wire feeding speed - welding current to the current compensation value.

[0014] In the above technical solution, the computing unit sends the welding torch adjustment signal to the actuator, which then controls the motor to adjust the height of the welding torch relative to the base material.

[0015] The technical solution of this invention addresses the issue of automatic control of welding extension length by manually adjusting the real-time welding current during all-position welding. Through linear regression, it establishes the relationship between parameters at different positions, thus avoiding the complex process of building an arc mathematical model and indirectly obtaining the control range of the welding extension length. This allows for control of the welding extension height by adjusting the current. This invention avoids the adaptability problem of model control under complex welding conditions, eliminating the need for arc model control theory and directly controlling wire feed speed and welding current. Using a result-oriented approach, it indirectly solves the problem of automatic control of the welding extension length adjustment, showing better adaptability to extension control in all-position welding systems. It also frees up manual intervention in the welding process, achieving partial intelligent operation. This method is highly adaptable, convenient to control, and guarantees accuracy. Attached Figure Description

[0016] Figure 1 This is a curve of wire feed speed versus welding current using linear fitting in this invention.

[0017] Figure 2 This is a schematic diagram of the welding segment positions in this invention.

[0018] Figure 3 This is a schematic diagram of the vertical position adjustment of the welding torch in this invention.

[0019] Figure 4 This is a current compensation diagram of the welding torch at different positions in this invention.

[0020] Figure 5 This is a flowchart of the dry stretch length control process in this invention.

[0021] Figure 6 This is a schematic diagram illustrating the implementation of the dry stretch length control in this invention.

[0022] Figure 7 These are actual weld formation diagrams for flat welding, vertical welding, and overhead welding in this invention. Detailed Implementation

[0023] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0024] The implementation process utilizes the Aotai PulseMIG-500 welding power supply, which features a unified control mode that automatically matches the welding current and voltage to a given wire feed speed. After inputting the wire feed speed on the control system's touchscreen, the system automatically calculates the corresponding welding current (denoted as current a) using a linear fitting formula. By measuring the welding current at different welding speeds, polynomial fitting is performed using MATLAB, and the curve fitting data is read as follows: Figure 1 As shown. From Figure 1 Based on the fitting results shown, the evaluation value of the fitted curve is SSE=149.8, and R0 is...2 =0.998, Adjusted R 2 =0.998, RMSE=1.53, the data is better, the linearity of the curve is better, and the linear regression equation is denoted as: y represents the welding current value, and x represents the wire feed speed value. The welding current can be adjusted by controlling the wire feed speed.

[0025] For all-position welding of steel pipes, an all-position automatic welding segmented welding scheme is proposed. The welding torch welds from position 0 to position 6, divided into three stages: flat welding position (0 to 2), vertical welding position (2 to 4), and overhead welding position (4 to 6). Each segment is 15°, for a total of 13 segments. Figure 2 As shown. By operating the handheld box, control commands are sent to the control system. The control system then sends up / down adjustment commands to drive the actuator. The actuator adjusts the height of the welding torch at different positions by changing the torch's vertical position. Figure 3 As shown, the extension length during all-position welding is indirectly controlled by adjusting the height of the welding torch.

[0026] The experiment employed a welding method from the 0-point to the 6-point position, divided into 13 welding positions. Following welding process standards, welding was performed in all positions at wire feed speeds ranging from 6 m / min to 12 m / min, and the all-position current compensation values ​​were obtained. Establish the relationship between different locations and current compensation values, such as Figure 4 As shown. According to Figure 4 The all-position current compensation data table is shown below.

[0027] Simplified table of all-position welding current compensation values

[0028]

[0029] Using the above methods, a linear regression equation for "wire feed speed - welding current" and a control scheme for all-position current compensation values ​​are obtained, which serve as the system current reference during the welding process.

[0030] The welding process employs a control system comprising four parts: a current sensor, a data acquisition card, a processing unit, and an actuator. Figure 5 As shown.

[0031] A current sensor collects welding current in real time, and the acquisition card converts the collected current signal into a digital signal and transmits it to the processing unit. The processing unit, based on the real-time welding angle at all positions, calls up a current compensation value, denoted as compensation value b. The previous current a is added to the compensation current value b to obtain the current reference value at that position.

[0032] At this point, the current acquisition value is compared with the current reference value, and an adjustment threshold is used to determine whether to adjust the welding torch position. Based on the determination result, the processing unit sends the welding torch adjustment signal to the actuator, which controls the motor to adjust the height position between the welding torch and the base material. After adjustment, the welding torch position is updated, and the welding current is again acquired in real time by the current sensor. The above process is repeated. Figure 6 As shown. By establishing a regression equation between wire feed speed and welding current, a segmented current compensation method for all positions is implemented, avoiding the use of an arc model for control. Welding process experiments are conducted to obtain theoretical and compensated current values ​​at suitable torch heights for different wire feed speeds and welding positions. The all-position adaptability range of the current data is determined, indirectly obtaining the requirements for the extension length at different positions. Through actual welding, it can be seen that in flat, vertical, and overhead welding positions, this method can ensure the uniformity of the weld height and the aesthetic appearance of the weld layer. Figure 7 As shown.

[0033] The present invention has been described above by way of example. It should be noted that any simple modifications, alterations or other equivalent substitutions that can be made by those skilled in the art without creative effort without departing from the core of the present invention fall within the protection scope of the present invention.

Claims

1. A method for controlling the stick-out length of gas shielded welding without a mold, characterized in that, include: A welding power source that automatically matches the corresponding welding voltage and current at a given wire feed speed is used. The welding current corresponding to different wire feed speeds is measured, and polynomial fitting is performed using MATLAB. The curve fitting data is read. The curve fitting data is a linear equation of wire feed speed and welding current. The welding current corresponding to the input wire feed speed is automatically calculated using the linear fitting formula of the programming system. In the process of automatic welding of pipe cross sections in all positions, the extension length of the welding torch is indirectly controlled by adjusting the height of the welding torch. According to the welding process standard requirements, the welding in all positions is completed within the set wire feeding speed range, the current compensation value of all positions is obtained, and the relationship between different welding positions and current compensation values ​​is established. During the all-position automatic welding process of the pipe section, the wire feeding speed setpoints at different positions are called in real time. The corresponding welding current and current compensation value are calculated by the linear equation of wire feeding speed and welding current. The sum of the two is used as the current reference value at that position. The real-time value and the reference value are compared to determine the difference in current magnitude. The upper and lower positions of the welding torch are adjusted according to the set adjustment threshold, thereby adjusting the extension length.

2. The method for controlling the stick-out length of gas shielded welding without a mold according to claim 1, characterized in that, Welding current is collected using a current sensor.

3. The method for controlling the stick-out length of gas shielded welding without a mold according to claim 1, characterized in that, The vertical position of the welding torch is adjusted by an actuator.

4. The method for controlling the stick-out length of gas shielded welding without a mold according to claim 1, characterized in that, An angle sensor is used to obtain the position information of the welding torch.

5. The method for controlling the stick-out length of gas shielded welding without a mold according to claim 1, characterized in that, The acquisition card converts the welding current signal into a digital signal and transmits it to the processing unit.

6. The method for controlling the stick-out length of gas shielded welding without a mold according to claim 1, characterized in that, The calculation unit calls the current compensation value based on the real-time welding angle at all positions, and adds the welding current to the current compensation value to obtain the current reference value at that position.

7. The method for controlling the stick-out length of gas shielded welding without a mold according to claim 1, characterized in that, The processing unit sends the welding torch adjustment signal to the actuator, which then controls the motor to adjust the height of the welding torch relative to the base material.

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