Construction method of novel annular laser heat source

Abstract

The invention relates to a construction method of a novel annular laser heat source, aims to solve the problem that good results of materials such as thin plate aluminum alloy and stainless steel are difficult to obtain in the existing annular laser welding simulation process, and provides a novel laser heat source with adaptive matching of geometric characteristics of an annular welding seam and controllable energy distribution. The method comprises the following steps: step 1, defining geometric parameters in assumption; 2, deducing an energy distribution formula of the laser; and 3, programming the constructed energy distribution function of the annular laser heat source through programming software, and then running the energy distribution function in commercial fluid simulation software.

Description

Technical Field

[0001] The present invention relates to the field of laser welding simulation, and particularly to a method for constructing a new type of annular laser heat source. Background Art

[0002] Laser welding technology is widely used in the fields of aerospace, new energy vehicles, and precision manufacturing due to its advantages such as high precision and low heat influence. However, the traditional laser heat source energy distribution model (such as Gaussian distribution) faces significant limitations in specific scenarios: First, for annular welds (such as pipe sealing and bearing seat ring welding), the Gaussian energy center aggregation characteristic easily leads to overheating in the central region of the annular seam and insufficient penetration at the edge, and complex path planning is required to compensate for the uneven energy; Second, when welding high-reflectivity materials (such as aluminum alloy), the solid surface reflectivity is high, and due to the mismatch of the energy distribution of the traditional heat source, an ultra-high power is required to trigger the molten pool, resulting in problems such as low efficiency and many spatterings; Third, in thin plate or surface treatment scenarios, the Gaussian distribution axial attenuation model is difficult to precisely control the penetration depth, and it is easy to cause burn-through or thermal deformation.

[0003] To address the above problems, the prior art attempts to optimize the energy distribution through multi-beam superposition or oscillating welding, but this increases the complexity of the optical system and it is difficult to ensure the energy consistency in the annular region. In addition, for the welding of annular structures, some solutions adopt the method of mechanically rotating the workpiece or the laser head, but the efficiency is low and it is not applicable to large components. Therefore, there is an urgent need for a new type of laser heat source model that can adaptively match the geometric characteristics of annular welds and has a controllable energy distribution.

[0004] The present invention proposes a method for constructing a new type of annular laser heat source. By establishing a three-dimensional energy model with a radially uniform distribution and an axially exponential attenuation, precise control of the energy in the annular region is achieved. This model eliminates the central energy redundancy in the plane and quantitatively constrains the penetration depth along the thickness direction through the attenuation coefficient, and is particularly suitable for the annular welding of materials such as thin plate aluminum alloy and stainless steel. Its innovation lies in: 1) Through the derivation of the normalized total energy formula, it ensures the direct correlation between the heat input and the process parameters; 2) The annular energy distribution matches the geometry of the annular weld and can be used as a simulation heat source for thin plates in annular conduction welding and surface treatment; 3) The axial attenuation coefficient is adjustable to adapt to different material thicknesses and penetration depth requirements. Summary of the Invention

[0005] The present invention aims to solve the problem that it is difficult to obtain good results in the existing annular laser welding simulation of materials such as thin plate aluminum alloy and stainless steel, and thus provides a new type of laser heat source that can adaptively match the geometric characteristics of annular welds and has a controllable energy distribution. The method for constructing a new type of annular laser heat source of the present invention is implemented according to the following steps:

[0006] Step 1: Define geometric parameters and assumptions;

[0007] (1) Annular region: with inner radius r1, outer radius r2, and total power P r .

[0008] (2) Axial attenuation: The three-dimensional energy density decays exponentially along the thickness direction (z-direction). Let the energy distribution function of the heat source be:

[0009] q(r, z) = Ce -μz (1)

[0010] In the above formula: C is the normalization constant, which needs to be determined by the conservation of total power; μ is the attenuation coefficient.

[0011] (3) Uniform distribution: Within the annular region (r1 ≤ r ≤ r2), the energy density is uniformly distributed in the planes of different thicknesses.

[0012] Step 2: Derivation of the energy distribution formula of the shaped laser;

[0013] The total power P r should be equal to the energy integral in three-dimensional space, that is:

[0014]

[0015] Solving for the normalization constant:

[0016]

[0017] Substituting the normalization constant C into formula (1), the energy distribution function of the annular laser is obtained as:

[0018]

[0019] Among them, as long as the heat source height H, heat source power P r , attenuation coefficient μ, inner radius r1, and outer radius r2 of the annular region are given, substituting the given values into formula (3) can calculate the specific energy distribution of the annular laser.

[0020] Step 3: Run the energy distribution function of the constructed annular laser heat source in a commercial fluid simulation software after programming through a programming software.

[0021] Preferably, in the method for constructing a novel annular laser heat source, the energy density on the heat source surface (z = 0) is:

[0022]

[0023] Preferably, in the method for constructing a novel annular laser heat source, the heat source can be used as an annular conduction weld for thin plates and a simulated heat source for surface treatment.

[0024] Preferably, in the method for constructing a novel annular laser heat source, the energy distribution of the heat source exponentially decays with the depth z, and the decay rate is controlled by the decay coefficient μ.

[0025] Preferably, the decay coefficient μ is taken as the reciprocal of three times the depth of the annular weld. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following-described drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings, where:

[0027] Figure 1 is a schematic diagram of the annular laser heat source distribution;

[0028] Figure 2 is a schematic diagram of the loading of the annular laser heat source distribution;

[0029] Figure 3 is a three-dimensional effect diagram of the annular laser heat source;

[0030] Figure 4 is a top view effect diagram of the annular laser heat source.

[0031] In the figure, 1 - annular region, 2 - annular laser distribution along the thickness, 3 - air model, 4 - base material, 5 - annular laser, 6 - front view effect after loading the annular laser heat source, 7 - three-dimensional effect of the annular laser heat source, 8 - top view effect of the annular laser heat source. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. The specific embodiments / embodiments recorded herein are specific specific embodiments of the present invention for explaining the concept of the present invention, and are all explanatory and exemplary, and should not be construed as limiting the embodiments of the present invention and the scope of the present invention. Except for the embodiments recorded herein, those skilled in the art can also adopt other obvious technical solutions based on the content disclosed in the claims and the specification of this application. These technical solutions include technical solutions that make any obvious substitutions and modifications to the embodiments recorded herein, and are all within the protection scope of the present invention.

[0033] The descriptions of the following embodiments refer to the attached drawings to illustrate specific embodiments in which the present invention can be implemented. The directional terms mentioned in the present invention, such as inside, outside, up, down, etc., only refer to the directions of the attached drawings. Therefore, the directional terms used are for explaining and understanding the present invention, rather than for limiting the present invention.

[0034] As Figures 1 to 4 shown, in the embodiment of the present invention, a method for constructing a novel annular laser heat source 100 is implemented according to the following steps:

[0035] Step 1: Define geometric parameters and assumptions;

[0036] (1) Annular region 1: inner radius r1, outer radius r2, and total power P r .

[0037] (2) Axial attenuation: The three-dimensional energy density decays exponentially along the thickness direction (z-direction). Let the energy distribution function of the heat source be:

[0038] q(r,z) = Ce -μz (1)

[0039] In the above formula: C is the normalization constant, which needs to be determined by the total power conservation; μ is the attenuation coefficient.

[0040] (3) Uniform distribution: In the annular region 1 (r1 ≤ r ≤ r2), the annular laser has the characteristic that the energy density is uniformly distributed in the planes at different thicknesses along the thickness distribution 2.

[0041] Step 2: Derive the energy distribution formula of the annular laser;

[0042] The total power P r should be equal to the energy integral in three-dimensional space, that is:

[0043]

[0044] Solve for the normalization constant:

[0045]

[0046] Substitute the normalization constant C into formula (1) to obtain the energy distribution function of the annular laser 5 as:

[0047]

[0048] Among them, as long as the heat source height H, heat source power P r , attenuation coefficient μ, inner radius r1, and outer radius r2 of the annular region 1 are given, substituting the given values into formula (3) can calculate the specific energy distribution of the annular laser 5.

[0049] Step 3: Program the energy distribution function of the constructed annular laser heat source 100 through programming software and run it in commercial fluid simulation software.

[0050] Preferably, the method for constructing the novel ring laser heat source 100 is characterized in that the surface energy density of the heat source (z=0) is:

[0051]

[0052] Preferably, the method for constructing the novel annular laser heat source 100 is characterized in that the heat source can be used as a simulated heat source for annular conduction welding and surface treatment of thin plates.

[0053] Preferably, the method for constructing the novel ring laser heat source 100 is characterized in that the energy distribution of the heat source decays exponentially with depth z, and the decay rate is controlled by the attenuation coefficient μ.

[0054] Preferably, the attenuation coefficient μ is 3 times the inverse of the annular weld depth.

[0055] This embodiment uses the ring beam heat source 100 loading method to realize aluminum alloy welding simulation. The specific steps are as follows:

[0056] Step 1: Heat source model programming;

[0057] Formula programming of the ring beam heat source 100 is performed in the Dev-C++ development environment.

[0058] Step 2: FLUENT numerical simulation;

[0059] (1) Establishing geometric model

[0060] A semi-structured model 200 with symmetry in the width direction is adopted.

[0061] (a) Semi-structured model 200 layered structure

[0062] Upper air space 3: thickness 2 mm, width 2 mm, length 7 mm;

[0063] Lower aluminum alloy base material 4: thickness 4 mm, width 2 mm, length 7 mm.

[0064] (b) Grid division scheme

[0065] All areas: 0.1mm×0.1mm×0.1mm

[0066] Total mesh volume: 84,000 hexahedral elements.

[0067] (2) Heat source parameter setting

[0068] Loading position: the center area of the upper surface of the base material 4;

[0069] Total power Q: 1kW;

[0070] Action depth H: 2mm;

[0071] Attenuation coefficient μ: 1500;

[0072] Geometric parameters: The outer radius r1 of the inner ring of the upper end surface of the heat source is 0.3 mm, and the inner radius r0 of the inner ring of the upper end surface of the heat source is 0.15 mm.

[0073] Step 3: Calculation result extraction

[0074] Termination condition: Stop the calculation when it reaches 0.005 ms.

[0075] Output the distribution results of the ring beam heat source 100 through the CFD-Post software, that is, the top view effect 8 after the ring beam heat source 100 is loaded, the three-dimensional effect 7 of the ring beam heat source 100, and the front view effect 6 after the ring beam heat source 100 is loaded.

[0076] Verification index: As can be seen from the top view effect 8 after being loaded by the annular laser 5, the high-temperature area affected by the annular laser 5 is mainly concentrated in the relatively shallow area of the surface layer of the base material 4, which proves that the ring beam heat source 100 can be used as a simulation heat source for the annular conduction welding and surface treatment of thin plates.

[0077] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent transformation made under the concept of the present invention by using the content of the specification and drawings of the present invention, or directly / indirectly applied in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A construction method of a novel annular laser heat source, characterized in that The construction method of the heat source is implemented according to the following steps: Step 1: Define geometric parameters and assumptions; (1) Annular region: inner radius r1, outer radius r2, total power P r . (2) Axial attenuation: The three-dimensional energy density decays exponentially along the thickness direction (z-direction). Let the energy distribution function of the heat source be: q(r,z) = Ce -μz (1) In the above formula: C is the normalization constant, which needs to be determined by the total power conservation; μ is the attenuation coefficient. (3) Uniform distribution: In the annular region (r1 ≤ r ≤ r2), the energy density is uniformly distributed in the planes at different thicknesses. Step 2: Derive the energy distribution formula of the annular laser; Total power P r should be equal to the energy integral in three-dimensional space, i.e.: Solve for the normalization constant: Substitute the normalization constant C into Equation (1) to obtain the energy distribution function of the annular laser as: Among them, as long as the heat source height H and the heat source power P are given r , the attenuation coefficient is μ, the inner radius r1 and the outer radius r2 of the annular region, substituting the given numerical values into Equation (3), the specific energy distribution of the annular laser can be calculated. Step 3: Program the energy distribution function of the constructed annular laser heat source through programming software and run it in commercial fluid simulation software.

2. The construction method of a novel annular laser heat source according to claim 1, characterized in that The energy density on the surface of the heat source (z = 0) is:

3. The construction method of a novel annular laser heat source according to claim 1, characterized in that The heat source can be used as a simulation heat source for annular conduction welding of thin plates and surface treatment.

4. A method for constructing a novel annular laser heat source according to claim 1, characterized in that The energy distribution of the heat source decays exponentially with the depth z, and the decay rate is controlled by the attenuation coefficient μ.

5. According to claim 4, the attenuation coefficient μ is taken as the reciprocal of 3 times the depth of the annular weld.

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