Welding quality prediction method based on supersonic pulse current and arc ultrasonic effect

Abstract

The present invention provides a welding quality prediction method based on super-frequency pulse current and arc ultrasonic effect, comprising the following steps: establishing a geometric model, meshing the model to form a three-dimensional structured network model; calculating super-frequency pulse current; calculating the electromagnetic force under the super-frequency pulse current; coupling the arc ultrasonic field and the electromagnetic force into the momentum conservation equation, establishing an arc ultrasonic field and electromagnetic force coupling model under the super-frequency pulse current; loading the established arc ultrasonic field and electromagnetic force coupling model into the three-dimensional structured network model, setting boundary conditions for simulation analysis, and obtaining the dynamic behavior change of the arc under the super-frequency pulse current to predict the welding quality. This method introduces the arc ultrasonic generation mechanism in the welding process, and can accurately predict the welding quality through simulation, thereby providing reliable data support for optimizing welding parameters.

Description

Technical Field

[0001] The present invention mainly relates to welding related technical fields, and specifically to a welding quality prediction method based on ultrasonic pulse current and arc ultrasonic effect. Background Art

[0002] Ultrasonic pulse current assisted welding is an advanced welding technology that significantly improves the stability of the welding arc and the welding quality by converting electrical energy into heat energy and introducing ultrasonic vibrations. This improvement is more significant in underwater wet welding. In an underwater environment, the welding process is strongly affected by the surrounding water medium. The stability of the arc and the quality of the weld formation are key factors affecting the performance of the welded joint. Especially in corrosive marine environments or high-pressure underwater operations, the welding quality is directly related to the safety and service life of the structure. Ultrasonic pulse current can not only improve the concentration and stability of the welding arc, but also produce an ultrasonic effect in the arc area. This effect helps to reduce pores and inclusions in the weld and improve the density and mechanical properties of the weld.

[0003] In ultrasonic pulse current assisted welding, the study of the influence of arc ultrasound generation still faces many challenges. First, the high-frequency vibration characteristics generated by the high-frequency pulse electromagnetic force generated by the ultrasonic pulse current will cause high-intensity ultrasonic waves to be generated in the arc area. Although this ultrasonic vibration helps to improve the quality of the weld, it may also cause violent vibrations of the molten metal and affect the forming quality of the weld. In addition, when underwater welding is performed, the complexity of the underwater environment further increases the difficulty of studying the mechanism of arc ultrasound generation. Especially when performing underwater wet welding, the arc is indirectly in contact with the water environment through bubbles, and the bubbles are easily affected by the surrounding water environment, which increases the difficulty of research.

[0004] Establishing a reasonable arc ultrasonic generation mechanism model is crucial in simulation and practical applications. Due to the complex interaction between ultrasonic pulse current and arc area. Traditional welding models usually apply ultrasonic waves directly to the arc through ultrasonic transducers, which greatly reduces the effect of ultrasonic waves on the welding molten pool and makes it difficult to accurately describe the generation and influence of ultrasonic waves in the arc. Therefore, it is difficult to accurately analyze and simulate the actual welding process through traditional models, and there are obvious deficiencies in the prediction of welding quality. Therefore, it is necessary to develop a new model to accurately analyze the generation and propagation of arc ultrasound after the introduction of ultrasonic pulse current in the welding process, so as to achieve accurate prediction of welding quality, so that the welding process can be optimized and controlled through simulation prediction results to improve the overall quality and reliability of welding. Summary of the invention

[0005] In order to solve the shortcomings of the current technology, the present invention combines the existing technology and, starting from practical applications, provides a welding quality prediction method based on ultrasonic pulse current and arc ultrasonic effect. This method introduces the arc ultrasonic generation mechanism during the welding process, and can accurately predict the welding quality through simulation, thereby providing reliable data support for optimizing welding parameters.

[0006] The technical solution of the present invention is as follows:

[0007] The welding quality prediction method based on supersonic pulse current and arc ultrasonic effect includes the following steps:

[0008] S1. Establish a geometric model and mesh the model to form a three-dimensional structured network model to simulate the dynamic behavior changes of the arc and its surrounding area under the action of ultrasonic pulse current;

[0009] S2, calculate the super-audio pulse current;

[0010] S3. Calculate the electromagnetic force under the action of super-audio pulse current;

[0011] S4. Couple the arc ultrasonic field and electromagnetic force into the momentum conservation equation, and establish a coupling model of the arc ultrasonic field and electromagnetic force under the action of super-frequency pulse current;

[0012] S5. Load the established arc ultrasonic field and electromagnetic force coupling model into the three-dimensional structured network model, set the boundary conditions for simulation analysis, solve the control equation, and obtain the changes in the dynamic behavior of the arc under the action of the ultrasonic pulse current to predict the welding quality.

[0013] Furthermore, in step S1, the weld and its surrounding area are meshed using a finite difference method, a finite element method or a finite volume method.

[0014] Further, the calculation of the ultrasonic pulse current in step S2 specifically includes:

[0015] The pulse period is The super-audio pulse current can be expressed as a series of Fourier series, as follows:

[0016] (1)

[0017] in, , and are Fourier coefficients, which can be calculated by the following formulas:

[0018] (2)

[0019] (3)

[0020] (4)

[0021] Combining formulas (1)-(4), the super-audio pulse current is expressed as:

[0022] (5)

[0023] in, is the base current, is the peak current, is the duty cycle, is the pulse frequency, For time, , is the angular frequency, is an integer.

[0024] Furthermore, in step S3, only the electromagnetic force acting on the arc is considered when calculating the electromagnetic force, and the arc shape is simplified to an isosceles triangle with an arc radius of R. It is assumed that after the current enters the arc space, it diverges in the entire arc area in a uniform manner.

[0025] Further, in step S3, the electromagnetic force is calculated as follows:

[0026] Assume that the current line of the shunt is perpendicular to the vertical axis of the coordinate system. The angle between the axes is , super-audio pulse current Direction of magnetic field strength It is expressed as follows:

[0027] (6)

[0028] Ultra-audio pulse current at the level The current density generated in the direction It is expressed as follows:

[0029] (7)

[0030] Ultrasonic pulse current Direction of electromagnetic force It is expressed as follows:

[0031] (8)

[0032] Combining formulas (6)-(8), we can obtain the arc space under the action of super-audio pulse current: The electromagnetic force expression of the direction is:

[0033] (9)

[0034] Ultrasonic pulse current Direction of magnetic field strength It is expressed as follows:

[0035] (10)

[0036] Ultrasonic pulse current The current density generated in the direction It is expressed as follows:

[0037] (11)

[0038] Ultrasonic pulse current Direction of electromagnetic force It is expressed as follows:

[0039] (12)

[0040] Combining formulas (10)-(12), we finally get the arc space under the action of super-audio pulse current: The electromagnetic force expression of the direction is:

[0041] (13)

[0042] in, is the vacuum permeability, is the base current, is the peak current, is the duty cycle, It is a super-audio pulse current.

[0043] Further, in step S4, the arc ultrasonic field equation is expressed as follows:

[0044] (14)

[0045] in, is the arc ultrasonic propagation velocity, is the arc ultrasonic pressure, is the arc plasma density.

[0046] Further, in step S4, the momentum conservation equation is expressed as follows:

[0047] (15)

[0048] in, is the arc plasma density, is the arc plasma velocity, For pressure, is the stress tensor, is the acceleration due to gravity, is the current density under the action of super-audio pulse current, is the magnetic induction intensity under the action of super-audio pulse current, is the surface tension, It is the acoustic radiation force generated by the arc ultrasonic field.

[0049] Beneficial effects of the present invention:

[0050] 1. The present invention provides a novel welding quality prediction method based on ultrasonic pulse current and arc ultrasound. By coupling arc ultrasound with electromagnetic force, it can not only accurately explain the mechanism of ultrasonic pulse current generating ultrasound in the arc space, but also describe the changes in the interaction behavior between high-frequency pulse electromagnetic force and the ultrasonic field generated by it and arc plasma. Through this method, the generation of arc ultrasound during welding and its interaction with the arc and molten metal can be effectively predicted, thereby providing reliable data support for optimizing welding parameters, improving the stability of welding process and weld quality, especially underwater wet welding in harsh welding environment.

[0051] 2. The method of the present invention is verified by simulation and is applicable to both onshore welding and underwater welding. The simulation prediction results are highly consistent with the actual weld morphology and have high accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 It is a schematic diagram of the ultrasonic pulse current waveform of the present invention.

[0053] Figure 2 It is a schematic diagram of current density distribution in the arc space of the present invention.

[0054] Figure 3 It is a schematic diagram of arc ultrasound generation of the present invention.

[0055] Figure 4 The figure is a comparison between the predicted and experimental droplet transfer processes of the present invention.

[0056] Figure 5 Comparison chart of arc temperature calculation results and experimental results.

[0057] Figure 6 Comparison chart of calculation results and experimental results of underwater FCAW bubble dynamic evolution process.

[0058] Figure 7 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0059] The present invention will be further described with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope limited by the application.

[0060] Example 1

[0061] This embodiment provides a welding quality prediction method based on ultrasonic pulse current and arc ultrasonic effect, which mainly includes the following steps.

[0062] Step 1: Create a geometric model.

[0063] The model is meshed using the finite difference method, finite element method or finite volume method. In order to improve the accuracy of the calculation, fine meshing is performed in the weld and surrounding areas, and a three-dimensional structured mesh model is established. This model will be used to simulate the dynamic behavior changes of the arc and its surrounding areas under the action of the ultrasonic pulse current, where the dynamic behavior mainly includes the temperature, flow velocity, current density and electromagnetic force distribution inside the arc plasma and the changes in the arc shape.

[0064] Step 2: Calculate the super-audio pulse current and obtain the pulse current calculation formula.

[0065] Based on Dirichlet theory, the pulse period is Ultra-audio pulse current (such as Figure 1 As shown in Figure 2, it can be expressed as a series of Fourier series, which can be expressed as follows:

[0066] (1)

[0067] in, , and are Fourier coefficients, which can be calculated by the following formulas:

[0068] (2)

[0069] (3)

[0070] (4)

[0071] Combining formulas (1)-(4), the super-audio pulse current can be expressed as:

[0072] (5)

[0073] in, is the base current, is the peak current, is the duty cycle, is the pulse frequency, For time, .

[0074] Step 3: Calculate the electromagnetic force under the action of the supersonic frequency pulse current and obtain the electromagnetic force calculation formula.

[0075] To simplify the analysis, only the electromagnetic force acting on the arc is considered. The arc shape is simplified to an isosceles triangle, and the arc radius is It is assumed that after the current enters the arc space, it diverges uniformly throughout the arc area. To further simplify the calculation, the current line of the shunt is parallel to the positive and negative coordinates of the coordinate system. The angle between the axes is ,like Figure 2 shown.

[0076] Based on electromagnetic field theory, the ultrasonic pulse current Direction of magnetic field strength It can be expressed as:

[0077] (6)

[0078] in, is the magnetic permeability of vacuum.

[0079] Ultrasonic pulse current The current density generated in the direction It can be expressed as:

[0080] (7)

[0081] Ultrasonic pulse current Direction of electromagnetic force It can be expressed as:

[0082] (8)

[0083] Combining formulas (6)-(8), we can finally obtain the arc space under the action of super-audio pulse current: The electromagnetic force expression of the direction is:

[0084] (9)

[0085] Ultrasonic pulse current Direction of magnetic field strength It can be expressed as:

[0086] (10)

[0087] Ultrasonic pulse current The current density generated in the direction It can be expressed as:

[0088] (11)

[0089] Ultrasonic pulse current Direction of electromagnetic force It can be expressed as:

[0090] (12)

[0091] Combining formulas (10)-(12), we can finally obtain the arc space under the action of super-audio pulse current: The electromagnetic force expression of the direction is:

[0092] (13)

[0093] When the supersonic frequency pulse current is applied, the rapidly changing electromagnetic force generated by it excites the plasma in the arc to vibrate, thereby exciting the arc to produce ultrasonic waves. According to formulas (9) and (13), after the introduction of the supersonic frequency pulse current, the arc plasma will be subjected to periodic contraction and expansion, and its change frequency is the same as the supersonic frequency pulse frequency. When the change frequency exceeds 20kHz, the arc itself will excite ultrasonic waves, namely arc ultrasound, such as Figure 3 shown.

[0094] It can be seen that when the arc is subjected to the action of super-audio pulse current, the current density in the arc and magnetic induction intensity The arc itself generates an ultrasonic field. The generation of arc ultrasound depends on the frequency of the ultrasonic pulse and the frequency of the arc shape change. The change of the arc shape depends on the electromagnetic force it receives. and The electromagnetic forces in the directions are calculated using formula (13) and formula (12) respectively.

[0095] Step 4: Establish the coupling model.

[0096] The arc ultrasonic field and electromagnetic force coupling model under the action of super-frequency pulse current is established, and the model takes into account the generation mechanism of arc ultrasound. The ultrasonic field expression is as follows:

[0097] (14)

[0098] in, is the arc ultrasonic propagation velocity, is the arc ultrasonic pressure.

[0099] The above ultrasonic field expression (14) and electromagnetic force expressions (12) and (13) are coupled to the momentum conservation equation and added into the momentum conservation equation in the form of momentum source term. The momentum conservation equation is expressed as follows:

[0100] (15)

[0101] in, is the arc plasma density, is the arc plasma velocity, For pressure, is the stress tensor, is the acceleration due to gravity, is the current density under the action of super-audio pulse current, is the magnetic induction intensity under the action of super-audio pulse current, is the surface tension, It is the acoustic radiation force generated by the arc ultrasonic field.

[0102] In the actual calculation process, the above parameters are the results obtained by iteratively updating the equation step by step. When calculating, an initial value is given to the parameter, and then the data is updated iteratively. When the calculation reaches a stable state, the default is the final calculation result. For different welding methods or welding conditions, the initial values ​​of the above physical quantities are set according to the actual situation.

[0103] Step 5: Simulation solution.

[0104] The simulation method is used for simulation calculation. The coupling model established in step 4 is loaded onto the geometric model in step 1, and the boundary conditions are set to perform numerical simulation calculations of the arc behavior. The control equation is solved by simulation software to obtain the changes in the dynamic behavior of the arc under the action of the ultrasonic pulse current, and then the welding quality prediction results are obtained. It should be understood that when performing simulation calculations and analysis of welding, the solution of the control equation is a joint solution, that is, the mass conservation equation, the momentum conservation equation, the energy conservation equation and the Maxwell equations are jointly solved. In this embodiment, the mass conservation equation, the energy conservation equation and the Maxwell equations are not improved, and the traditional expression method is still used. The momentum conservation equation is calculated using the coupling model obtained in this embodiment. After the momentum equation is updated and improved, the changes in the temperature, flow rate, current density and electromagnetic force distribution inside the arc plasma and the arc shape obtained by simulation are closer to the real value.

[0105] Example 2

[0106] This embodiment uses the GMAW welding process of Q235 low carbon steel as an example to perform simulation calculations to verify the beneficial effects of the present invention.

[0107] The base material used in the experiment is Q235 low carbon steel, the workpiece size is 70mm×35mm×5mm, the wire diameter is 1.2mm, and the GMAW welding machine model used in the experiment is Aotai PULSE MIG500. The welding parameters are MIG current 250A, welding speed 1.5 m / min, and the verification steps are as follows.

[0108] Step 1: Establish a geometric model, divide the model using the finite difference method, and perform mesh subdivision on the weld and surrounding areas.

[0109] Step 2: Load the coupling model provided by the present invention;

[0110] Step 3: Use simulation methods to calculate the changes in the dynamic behavior of the arc.

[0111] In order to verify the accuracy of the model calculation results, the calculation results are compared with the actual weld morphology, such as Figure 4 As shown in the figure, (a) is the actual welding data, and (b) is the simulation result. By comparison, it can be seen that the two are highly consistent. Figure 5 (a) is the arc image taken during the experiment. Figure 5 (b) is the arc temperature experimental measurement result. Figure 5 (c) is the arc temperature calculation result. Figure 6 (a) is a comparison diagram of the bubble growth stage. Figure 6 (b) and (c) are comparison diagrams of the bubble necking stage. Figure 6 (d) is a comparison diagram of the bubble separation stage. Figure 5 and Figure 6 It can be seen that the calculated results are in good agreement with the experimental results, which also proves the accuracy of this method.

Claims

1. A welding quality prediction method based on supersonic pulse current and arc ultrasonic effect, characterized in that: The steps include: S1. Establish a geometric model and mesh the model to form a three-dimensional structured network model to simulate the dynamic behavior changes of the arc and its surrounding area under the action of ultrasonic pulse current; S2, calculate the super-audio pulse current; S3. Calculate the electromagnetic force under the action of super-audio pulse current; S4. The arc ultrasonic field and electromagnetic force are coupled to the momentum conservation equation, and a coupling model of the arc ultrasonic field and electromagnetic force under the action of the supersonic frequency pulse current is established. The arc ultrasonic field equation is expressed as follows: , in, is the arc ultrasonic propagation velocity, is the arc ultrasonic pressure, Arc plasma density, The momentum conservation equation is expressed as follows: , in, is the arc plasma density, is the arc plasma velocity, For pressure, is the stress tensor, is the acceleration due to gravity, is the current density under the action of super-audio pulse current, is the magnetic induction intensity under the action of super-audio pulse current, is the surface tension, It is the acoustic radiation force generated by the arc ultrasonic field; S5. Load the established arc ultrasonic field and electromagnetic force coupling model into the three-dimensional structured network model, set the boundary conditions for simulation analysis, and solve the control equation to obtain the changes in the dynamic behavior of the arc under the action of the ultrasonic pulse current to predict the welding quality.

2. The welding quality prediction method based on ultrasonic pulse current and arc ultrasonic effect according to claim 1 is characterized in that: In step S1, the weld and its surrounding area are meshed using a finite difference method, a finite element method, or a finite volume method.

3. The welding quality prediction method based on ultrasonic pulse current and arc ultrasonic effect according to claim 1 is characterized in that: In step S2, the super-audio pulse current The expression is as follows: in, is the base current, is the peak current, is the duty cycle, is the pulse frequency, For time, is an integer.

4. The welding quality prediction method based on ultrasonic pulse current and arc ultrasonic effect according to claim 1 is characterized in that: In step S3, the electromagnetic force is calculated by only considering the electromagnetic force acting on the arc, and the arc shape is simplified to an isosceles triangle with an arc radius of , assuming that the current enters the arc space and diverges uniformly throughout the arc region.

5. The welding quality prediction method based on ultrasonic pulse current and arc ultrasonic effect according to claim 4 is characterized in that: In step S3, when calculating the electromagnetic force, the vertical positive line of the shunt current is assumed to be The angle between the axes is , vertical arc space under the action of super-audio pulse current Direction of electromagnetic force The expression is as follows: , The arc space level under the action of super-audio pulse current Direction of electromagnetic force The expression is as follows: ,in, is the vacuum permeability, is the base current, is the peak current, is the duty cycle, It is a super-audio pulse current.

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