High-precision weld shape prediction method suitable for myriawatt laser welding

A technology of laser welding and prediction method, which is applied in the direction of instruments, complex mathematical operations, design optimization/simulation, etc., can solve the problem of low prediction accuracy of weld shape, and achieve high pressure calculation accuracy, good physical conservation, and stable calculation good sex effect

Pending Publication Date: 2022-08-02

CHANGSHU INSTITUTE OF TECHNOLOGY

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Problems solved by technology

[0005] In order to solve the problem of low weld seam shape prediction accuracy in 10,000-watt laser welding, the p...

Method used

Can't consider molten pool and plume coupling behavior and then cause the low problem of 10,000-watt laser welding seam shape prediction accuracy for existing weld shape prediction method, the present invention adopts the compressible two-...

Abstract

The invention discloses a high-precision weld joint morphology prediction method suitable for myriawatt-level laser welding, and aims to solve the problem that the weld joint morphology prediction precision of myriawatt-level laser welding is low due to the fact that a weld pool and plume coupling behavior cannot be considered in an existing weld joint morphology prediction method. According to the method, a compressible two-phase flow numerical calculation method based on pressure is adopted to solve the coupling behavior of the molten pool and plume, and therefore high-precision prediction of the myriawatt-level laser welding seam morphology is achieved. Firstly, a welding seam morphology function and welding parameters at the initial moment are input; secondly, a compressible two-phase flow numerical calculation method based on pressure is adopted to obtain a welding seam morphology function at the next moment; and drawing a welding seam morphology function at the next moment, and extracting welding seam morphology and welding seam morphology characteristics. Compared with an existing weld joint morphology prediction method, the weld pool and plume coupling behavior in myriawatt-level laser welding can be accurately calculated, the algorithm is simple and easy to implement, the calculation efficiency is high, the physical conservation is good, and high-precision prediction of the myriawatt-level laser welding weld joint morphology can be achieved.

Application Domain

Design optimisation/simulationManufacturing computing systems +1

Technology Topic

PhysicsWeld seam +6

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[0041] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0042] Aiming at the problem that the existing welding seam morphology prediction method cannot consider the coupling behavior of the molten pool and the plume, which leads to the low prediction accuracy of the 10,000-watt laser welding seam morphology, the present invention adopts the pressure-based compressible two-phase flow numerical calculation method to solve the problem. The coupling behavior of molten pool and plume can realize high-precision prediction of weld seam morphology of 10,000-watt laser welding.

[0043] combine figure 1 , a method for predicting high-precision weld seam morphology suitable for 10,000-watt laser welding according to the present invention, comprising the following steps:

[0044] Step 1: Input the weld profile function at the initial moment

[0045] The present invention uses the hyperbolic tangent function to represent the weld shape H n , the weld topography is defined as the 0.5 isosurface of the hyperbolic tangent function. The weld profile function H at the initial moment n See formula (1):

[0046]

[0047] where Δx min is the minimum grid size, φ n is the distance from each point in the workpiece section to the weld at the initial moment, and tanh is the hyperbolic tangent function, such as figure 2 shown.

[0048] Step 2: Determine the welding parameters at the initial moment

[0049] The welding parameters at the initial moment are shown in Table 1:

[0050] Table 1 Welding parameters at the initial moment

[0051]

[0052]

[0053] Step 3: Obtain the weld profile function H at the next moment n+1

[0054] The present invention proposes a pressure-based numerical calculation method for compressible two-phase flow to solve the weld topography function H at the next moment. n+1 , the specific implementation process is as follows:

[0055] ①Calculate the momentum source S at the initial moment n , see formula (2).

[0056]

[0057] in, represent the momentum sources caused by inertia, surface force, and body force, respectively, is the gradient operator, · is the divergence operator, superscript T stands for matrix transpose, ρ n , u n , T n , μ, α, T env , σ, A, B 0 , m, L, T s Given by Table 1, g is the gravitational acceleration constant, k b is the Boltzmann constant.

[0058] ②Calculate the energy source Q at the initial moment n , see equation (3).

[0059]

[0060] in, is the gradient operator, · is the divergence operator, ρ n , u n , T n , C p , λ, I, r 0 Given by Table 1, Given by formula (2), r is the distance from each point to the center of the laser spot.

[0061] ③ Calculate the density ρ after convection * , speed u * and temperature T * , see equation (4).

[0062]

[0063] in, is the gradient operator, is the divergence operator, Δt is the calculation time step, u n , T n , ρ n , u n , T n given in Table 1.

[0064] ④ Calculate the pressure p at the next moment n+1 , see equation (5).

[0065]

[0066] in, is the gradient operator, · is the divergence operator, Δt is the calculation time step, ρ*, u*, T* are obtained from formula (4), C V Given by Table 1, R is the ideal gas constant.

[0067] ⑤ Calculate the density ρ at the next moment n+1 , speed u n+1 , temperature T n+1 , see equation (6).

[0068]

[0069] in, is the gradient operator, · is the divergence operator, Δt is the calculation time step, ρ*, u*, T* are given by formula (4), C V Given by Table 1, R is the ideal gas constant.

[0070] ⑥ Calculate the weld profile function H at the next moment n+1 , see equation (7).

[0071]

[0072] in, is the gradient operator, Δt is the calculation time step, H n Given by formula (1), u n+1 is given by equation (6).

[0073] Among them, the gradient operator in formula (2) to formula (7) and the divergence operator ·The FiniteVolume Method is used for discretization to ensure strict physical field conservation.

[0074] Formula (5) can be solved by methods such as the Success Over Relaxation Method, the Conjugate Gradient Method or the Fast Fourier Transform.

[0075] Step 4: Draw the weld profile function H at the next moment n+1 distribution cloud map.

[0076] According to the weld topography function H at the next moment n+1 , draw the distribution cloud map of the weld topography function, such as image 3 shown.

[0077] Step 5: Extract the weld profile at the next moment.

[0078] According to the weld topography function H at the next moment n+1 , extract H n+1 The 0.5 isosurface is used as the weld morphology at the next moment, such as Figure 4 shown.

[0079] Step 6: Output the weld topography features at the next moment.

[0080] According to the weld profile at the next moment, output the weld profile features at the next moment, including weld width, penetration depth, and height, such as Figure 5 shown.

[0081] Compared with the existing welding seam shape prediction method, the invention can accurately calculate the coupling behavior of the molten pool and the plume in the 10,000-watt laser welding, the algorithm is simple and easy to implement, the calculation efficiency is high, and the physical conservation is good, and the 10,000-watt laser welding can be realized. High-precision prediction of seam topography in high-grade laser welding.

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High-precision weld shape prediction method suitable for myriawatt laser welding

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