Tool high-speed laser cladding repair method based on molten pool topography

Abstract

The application discloses a tool high-speed laser cladding repair method based on a molten pool shape and belongs to the technical field of additive manufacturing processing. The method is classified according to the shape size of the tool first, then a three-dimensional transient laser cladding mathematical model coupled with temperature and flow field is constructed, the relationship between the initial laser cladding process parameters and the molten pool shape of different categories of tools is obtained through simulation, and the corresponding initial parameters are formulated; subsequently, based on the initial molten pool shape, the repair parameters are matched in the preset laser cladding repair rule library, the camera installed at the end of the cladding device is used to shoot the shape size of the molten pool in real time, the process parameters are adjusted in real time through algorithm conversion into robot instructions, the high-speed laser cladding adaptive repair of the tool is realized, and the application can optimize the parameters in real time according to the tool specifications and the dynamic change of the molten pool, reduce the experimental verification cost, improve the repair efficiency and quality, and is suitable for the repair and reinforcement of various specifications of kitchen tools.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology, specifically relating to a high-speed laser cladding repair method for cutting tools based on the morphology of the molten pool. Background Technology

[0002] Laser additive manufacturing, as a rapidly developing digital advanced manufacturing technology, has been widely used in the rapid fabrication of metallic materials such as titanium alloys, stainless steel, and nickel-based alloys, as well as oxide ceramics. This technology mainly includes two methods: selective laser bed fusion (LPBF) and laser-directed energy deposition (LDED). Its principle is to use a high-energy laser to melt metal powder or wire layer by layer, forming a tiny molten pool. The molten pool then rapidly solidifies, gradually shaping a three-dimensional part according to a pre-planned path. With its significant advantages such as short cycle time, high precision and flexibility, and the ability to fabricate complex structural parts, laser additive manufacturing technology has demonstrated enormous application potential in numerous fields.

[0003] Kitchen knives are indispensable tools in daily life and the catering industry, and their performance directly affects the user experience and work efficiency. According to the GB / T 40356-2021 standard, the raw materials for kitchen knife blades cover stainless steel, carbon steel, alloy steel, and stainless steel composite steel knives. Among the various performance characteristics of a knife, sharpness and durability have the most critical impact on its usability. Using laser additive manufacturing to fuse wear-resistant materials onto the surface of ordinary stainless steel knives can significantly improve the knife's strength and wear resistance while reducing production costs, thus possessing a very broad market application prospect.

[0004] However, in practical applications, the cutting tools that need to be processed come in various specifications in terms of size, shape, and thickness. This means that during the laser cladding process, the corresponding process parameters must be adjusted according to the size of different cutting tools. This is not only time-consuming and labor-intensive, but also requires extensive experimental verification to obtain a process database that ultimately meets the usage requirements. This traditional method is difficult to adapt to diverse tool repair needs, is inefficient, and costly, thus limiting the further promotion and application of laser cladding technology in the field of tool repair.

[0005] Therefore, it is necessary to propose a high-speed laser cladding repair method for cutting tools based on the molten pool morphology. By monitoring the molten pool morphology in real time and dynamically adjusting the process parameters, the above-mentioned problems in the existing technology can be solved, thereby improving the efficiency and quality of laser cladding repair of cutting tools. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing laser cladding repair tools, which require repeated parameter adjustments based on different dimensions, resulting in low efficiency and high cost. This invention provides a high-speed laser cladding repair method for tools based on the morphology of the molten pool.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A high-speed laser cladding repair method for cutting tools based on molten pool morphology includes the following steps:

[0009] Step 1: Classify the cutting tools according to their external dimensions;

[0010] Step 2: Establish a three-dimensional transient laser cladding mathematical model that couples temperature and flow field, and predict the relationship between the initial laser cladding process parameters and the molten pool morphology for different types of cutting tools based on the simulation results;

[0011] Step 3: Based on the simulation results of Step 2, formulate initial high-speed laser cladding parameters for different types of cutting tools;

[0012] Step 4: Based on the initial molten pool morphology of different types of tools, the laser cladding repair parameters are matched in the pre-set laser cladding repair rule library. The molten pool morphology image is captured in real time by the camera installed on the laser cladding head and uploaded to the control terminal for data processing to obtain the molten pool morphology contour.

[0013] Step 5: The robot drives the laser cladding head to move along the cutting edge of the tool. During the laser cladding process, the laser cladding process parameters are adjusted in real time based on the initial laser cladding parameters according to the morphology of the molten pool, so as to complete the strengthening and repair of the tool.

[0014] In a preferred embodiment of the present invention, the tool classification criteria in step 1 are as follows: micro tools: length ≤ 60 mm, thickness ≤ 1 mm; small tools: length 60-100 mm, thickness 1-1.4 mm; medium tools: length 100-150 mm, thickness 1.4-1.8 mm; slightly large tools: length 150-220 mm, thickness 1.8-2.5 mm; large tools: length ≥ 220 mm, thickness ≥ 2.5 mm.

[0015] In a preferred embodiment of the present invention, in step 2, when establishing a three-dimensional transient laser cladding mathematical model coupled with temperature and flow field, the following assumptions are made for the mathematical model to ensure the computational efficiency and accuracy of the mathematical model: the initial temperature of laser cladding is defined as 293.15K; both the laser beam and the powder beam follow a Gaussian distribution; the thermal properties of the substrate and cladding layer materials, such as thermal conductivity, specific heat capacity, viscosity, and surface tension, are related to temperature; the influence of the evaporation backpressure caused by the evaporation of the molten pool on the molten pool is ignored; the molten metal in the molten pool is an incompressible Newtonian fluid, and the flow state is laminar.

[0016] In a preferred embodiment of the present invention, in step 2, the governing equations of the three-dimensional transient laser cladding mathematical model include heat transfer control equations and fluid flow control equations; the heat transfer control equations are:

[0017]

[0018] In the formula, ρ, c p k and ρ are the density, specific heat capacity, and thermal conductivity of the material, respectively, and T is the temperature. Here, σ is the temperature gradient, u is the velocity field, Q is the laser heat source energy, h is the convective heat transfer coefficient, ε is the material surface emissivity, and σ is the temperature gradient. b It is the Steffen-Boltzman constant, which is 5.67E. -8 W / (m 2 ·k 4 );T amb The ambient temperature is 293.15K. The second and third terms on the right side of the formula represent heat convection and heat radiation, respectively.

[0019] The fluid flow control equations include the Navier-Stokes momentum equation and the continuity equation;

[0020] Navier-Stokes momentum equation:

[0021] Continuity equation: In the formula, P is pressure, I is the unit tensor, and μ is dynamic viscosity. It is the viscosity gradient, and F is the volume force.

[0022] In a preferred embodiment of the present invention, in step 2, the heat transfer boundary conditions during the laser cladding process include thermal convection and thermal radiation:

[0023] Thermal convection boundary condition: -n·q=h(T) amb -T);

[0024] Thermal radiation boundary conditions:

[0025] In the formula, n is the boundary normal vector and q is the heat flux density.

[0026] In a preferred embodiment of the present invention, in step 2, the meshing of the thermal-fluid coupling model is based on the idea of ​​symmetry and only considers half of the model. The region where the molten pool grows is divided into a fine tetrahedral mesh with a maximum element size of 0.286 mm, while the region far from the molten pool is divided into a coarser tetrahedral mesh with a maximum element size of 0.944 mm. The entire model has a total of 23,479 domain elements.

[0027] In a preferred embodiment of the present invention, the initial high-speed laser cladding parameters for different types of cutting tools in step 3 are as follows: Micro-cutting tool: laser power 750W, scanning speed 15mm / s, powder feeding speed 1.35g / min; Small cutting tool: laser power 900W, scanning speed 18mm / s, powder feeding speed 1.85g / min; Medium cutting tool: laser power 1100W, scanning speed 22mm / s, powder feeding speed 2.45g / min; Slightly large cutting tool: laser power 1350W, scanning speed 25mm / s, powder feeding speed 3.20g / min; Large cutting tool: laser power 1500W, scanning speed 30mm / s, powder feeding speed 5.24g / min.

[0028] In a preferred embodiment of the present invention, in steps 4 and 5, the laser cladding repair parameters include cladding powder type, laser power, laser duration, protective gas flow rate, scanning speed, and powder feeding speed.

[0029] In a preferred embodiment of the present invention, the cladding powder type includes iron-based alloys, nickel-based alloys, cobalt-based alloys, and graphene / nano-based composite materials; wherein, the iron-based alloy is selected from 420 stainless steel or 420+TiC alloy; the nickel-based alloy is selected from Inconel 625, 7-series or 9-series; and the cobalt-based alloy is ST6+WC type.

[0030] In a preferred embodiment of the present invention, in step 4, a Gaussian surface heat source model is used to simulate the laser heat source, whose energy follows a normal distribution in space.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The present invention first classifies the cutting tools, then establishes mathematical models and sets initial parameters for different categories of cutting tools, making the parameter settings more targeted, reducing blindness, and laying a good foundation for subsequent real-time adjustments.

[0033] (2) The simulation using a three-dimensional transient laser cladding mathematical model that couples temperature and flow field can accurately predict the relationship between initial laser cladding process parameters and molten pool morphology, reducing a lot of experimental verification work, lowering costs and improving efficiency.

[0034] (3) By monitoring the morphology of the molten pool in real time through a camera and adjusting the process parameters in real time according to the morphology of the molten pool, adaptive repair is achieved, which can ensure that the final tool-strengthened product meets the requirements and improves the repair quality and stability.

[0035] (4) This invention is applicable to the repair of kitchen knives of various specifications and has wide applicability, which is conducive to the promotion and application of laser cladding technology in the field of knife repair. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments or prior art, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 A mesh diagram of a thermal-fluid coupling model provided for an embodiment of this application.

[0038] Figure 2 This is a dynamic growth diagram of the molten pool in the initial stage of laser cladding, provided as an embodiment of this application.

[0039] Figure 3 This is a diagram showing the size change of the molten pool during the initial stage of laser cladding, provided as an embodiment of this application.

[0040] Figure 4 An isotherm distribution diagram of a molten pool provided in an embodiment of this application.

[0041] Figure 5 This is a schematic diagram of the initial molten pool morphology of different cutting tools provided in the embodiments of this application.

[0042] Figure 6 This is a schematic diagram of the morphology of a processed molten pool provided in an embodiment of this application.

[0043] Figure 7 This is a schematic diagram illustrating how a robot, as provided in an embodiment of this application, drives a laser cladding head to move along the cutting edge of a tool and complete the tool strengthening process. Detailed Implementation

[0044] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application. The terms "upper," "lower," "front," "rear," "left," and "right," etc., used when describing the installation position or direction of the structure or components in this embodiment are based on the orientation shown in the accompanying drawings. They are merely for convenience of description, used to distinguish the relative positions of various components or directions, and do not represent the orientation of the device or functional component in this embodiment during use.

[0045] refer to Figures 1-7 This invention provides a high-speed laser cladding repair method for cutting tools based on molten pool morphology, comprising the following steps:

[0046] Step 1: Classify the cutting tools according to their external dimensions;

[0047] Step 2: Establish a three-dimensional transient laser cladding mathematical model that couples temperature and flow field, and predict the relationship between the initial laser cladding process parameters and the molten pool morphology for different types of cutting tools based on the simulation results;

[0048] Step 3: Based on the simulation results of Step 2, formulate initial high-speed laser cladding parameters for different types of cutting tools;

[0049] Step 4: Based on the initial molten pool morphology of different types of tools, the laser cladding repair parameters are matched in the pre-set laser cladding repair rule library. The molten pool morphology image is captured in real time by the camera installed on the laser cladding head and uploaded to the control terminal for data processing to obtain the molten pool morphology contour.

[0050] Step 5: The robot drives the laser cladding head to move along the cutting edge of the tool. During the laser cladding process, the laser cladding process parameters are adjusted in real time based on the initial laser cladding parameters according to the morphology of the molten pool, so as to complete the strengthening and repair of the tool.

[0051] Based on the dimensions of the cutting tools to be machined, the tools are summarized and classified into five categories: micro tools, small tools, medium tools, slightly large tools, and large tools. Referring to Table 1, the tool classification standards in step 1 are as follows: Micro tools: length ≤ 60mm, thickness ≤ 1mm; Small tools: length 60-100mm, thickness 1-1.4mm; Medium tools: length 100-150mm, thickness 1.4-1.8mm; Slightly large tools: length 150-220mm, thickness 1.8-2.5mm; Large tools: length ≥ 220mm, thickness ≥ 2.5mm.

[0052] Table 1. Classification of Cutting Tools

[0053] 1 ≤60 ≤1 Micro-tools 2 60-100 1-1.4 small knife 3 100-150 1.4-1.8 Medium-sized knives 4 150-220 1.8-2.5 Slightly larger knives 5 ≥220 ≥2.5 large knives

[0054] This classification method is based on the size range of common kitchen knives and is divided by two key parameters: length and thickness. This allows knives of different specifications to be clearly categorized, which facilitates the subsequent setting of targeted process parameters.

[0055] In step 2, when establishing the three-dimensional transient laser cladding mathematical model that couples temperature and flow field, the interaction between the laser beam and the powder was considered, and the control equations and boundary conditions that conform to the cladding experiment were defined. In order to ensure the computational efficiency and accuracy of the mathematical model, the following assumptions were made for the mathematical model: the initial temperature of laser cladding is defined as 293.15K; both the laser beam and the powder beam follow a Gaussian distribution; the thermal properties of the substrate and cladding layer materials, such as thermal conductivity, specific heat capacity, viscosity, and surface tension, are related to temperature; the influence of the evaporation backpressure caused by the evaporation of the molten pool on the molten pool is ignored; the molten metal in the molten pool is an incompressible Newtonian fluid, and the flow state is laminar.

[0056] In step 2, the governing equations of the three-dimensional transient laser cladding mathematical model include heat transfer control equations and fluid flow control equations; the heat transfer control equation is:

[0057]

[0058] In the formula, ρ, c p k and ρ are the density, specific heat capacity, and thermal conductivity of the material, respectively, and T is the temperature. Here, σ is the temperature gradient, u is the velocity field, Q is the laser heat source energy, h is the convective heat transfer coefficient, ε is the material surface emissivity, and σ is the temperature gradient. b It is the Steffen-Boltzman constant, which is 5.67E. -8 W / (m 2 ·k 4 );T amb The ambient temperature is 293.15K. The second and third terms on the right side of the formula represent thermal convection and thermal radiation, respectively.

[0059] A Gaussian surface heat source model is used to simulate the laser heat source. This model ensures both simulation accuracy and computational efficiency. Its energy follows a normal distribution in space, with the highest energy at the center of the heat source and decreasing outwards. Energy distribution formula:

[0060] The governing equations for fluid flow include the Navier-Stokes momentum equation and the continuity equation;

[0061] Navier-Stokes momentum equation:

[0062] Continuity equation: In the formula, P is pressure, I is the unit tensor, and μ is dynamic viscosity. It is the viscosity gradient, and F is the volume force.

[0063] In step 2, the heat transfer boundary conditions during laser cladding include thermal convection and thermal radiation:

[0064] Thermal convection boundary condition: -n·q=h(T) amb -T);

[0065] Thermal radiation boundary conditions:

[0066] In the formula, n is the boundary normal vector and q is the heat flux density.

[0067] In step 2, the mesh generation of the thermal-fluid coupling model is based on the principle of symmetry, considering only half of the model. The region where the molten pool grows is meshed with fine tetrahedral meshes, with a maximum element size of 0.286 mm. Regions farther from the molten pool are meshed with coarser tetrahedral meshes, with a maximum element size of 0.944 mm. The entire model contains 23479 domain elements. This approach ensures both the accuracy of the calculation results and improves the computational efficiency of the model. (Refer to...) Figure 1 .

[0068] Based on the simulation results in step 2, the initial high-speed laser cladding parameters for different cutting tools were determined. Referring to Table 2, the initial high-speed laser cladding parameters for different types of cutting tools in step 3 are as follows: Micro-cutting tool: laser power 750W, scanning speed 15mm / s, powder feeding speed 1.35g / min; Small cutting tool: laser power 900W, scanning speed 18mm / s, powder feeding speed 1.85g / min; Medium cutting tool: laser power 1100W, scanning speed 22mm / s, powder feeding speed 2.45g / min; Slightly larger cutting tool: laser power 1350W, scanning speed 25mm / s, powder feeding speed 3.20g / min; Large cutting tool: laser power 1500W, scanning speed 30mm / s, powder feeding speed 5.24g / min.

[0069] Table 2 Initial laser cladding parameters for different cutting tools

[0070]

[0071] In step 4, a Gaussian surface heat source model is used to simulate the laser heat source, whose energy follows a normal distribution in space.

[0072] Based on the initial molten pool morphology of different cutting tools, laser cladding repair parameters are obtained by matching them in a pre-set laser cladding repair rule library. In steps 4 and 5, the laser cladding repair parameters include cladding powder type, laser power, laser duration, protective gas flow rate, scanning speed, and powder feeding speed.

[0073] Cladding powder types include iron-based alloys, nickel-based alloys, cobalt-based alloys, and graphene / nano-based composites. Iron-based alloys are made of 420 stainless steel or 420+TiC alloy; nickel-based alloys are made of Inconel 625, 7-series, or 9-series; and cobalt-based alloys are ST6+WC. Different powder types offer different properties, allowing selection based on the tool's usage requirements and repair needs. For example, iron-based alloy powders are relatively inexpensive and suitable for general tool repair; nickel-based alloy powders offer good high-temperature resistance and corrosion resistance, making them suitable for tools in special environments; cobalt-based alloy powders have excellent wear resistance, making them suitable for tools requiring high wear resistance; and graphene / nano-based composites significantly improve the strength and hardness of the tool.

[0074] The above model is used to simulate the laser cladding process of different cutting tools. Figure 2 The dynamic growth process of the molten pool from 30ms to 150ms was shown when the laser power was 900W, the scanning speed was 8mm / s, and the powder feed rate was 2.36g / min. Figure 3 This is a diagram showing the dimensional changes in length, width, and depth during the growth of the molten pool. From... Figure 2 and Figure 3 As can be seen, the molten pool is relatively small in the initial stage of laser cladding, especially the length of the molten pool is relatively short. As cladding progresses, the length, width, and depth of the molten pool all increase continuously. The width and depth reach a stable state in a short time. The length of the molten pool increases the most, followed by the width, and the depth increases the least. The geometric dimensions and temperature of the molten pool reach a stable state at 120ms. At this time, the heat input and heat dissipation in the molten pool reach a balance, and the molten pool is in a dynamic equilibrium state. Figure 4 This is an isotherm distribution diagram of the molten pool during laser cladding. The molten pool is ellipsoidal in shape. The isotherms are densely distributed at the front end of the molten pool, indicating a uniform temperature distribution and a low temperature gradient. At the rear end of the molten pool, the isotherms are sparse, indicating a large temperature difference and a significant temperature gradient. These simulation results provide a theoretical basis for the subsequent determination of initial parameters.

[0075] like Figure 5 As shown, the initial molten pool morphology of different tools was obtained using the laser cladding parameters in Table 2 above. Due to the different sizes of the tools, the initial molten pool morphology of different types of tools is different, which is consistent with the simulation results and further verifies the rationality of the initial parameters.

[0076] The camera set up on the laser cladding head captured the image. Figure 5 The morphology image of the molten pool is obtained and uploaded to the control terminal for data processing, resulting in... Figure 6 The molten pool shape outline is shown. The data processing includes image preprocessing (such as noise reduction and enhancement), edge detection, and contour extraction to accurately obtain the molten pool's shape and size information, providing a basis for subsequent parameter adjustments.

[0077] like Figure 7 As shown, robot 2 drives laser cladding head 3 to move along the cutting edge of tool 1 and complete tool strengthening. During laser cladding, the control unit adjusts the laser cladding process parameters in real time based on the processed molten pool morphology profile 4, building upon the initial laser cladding parameters. For example, if the molten pool length is detected to be too large, the laser power can be appropriately reduced or the scanning speed increased to decrease the molten pool size; if the molten pool width or depth does not meet the requirements, it can be corrected by adjusting parameters such as powder feeding speed and laser duration. Through this real-time adjustment, the desired tool strengthening product is ensured. In this embodiment, a camera installed at the end of the cladding device captures the molten pool's external dimensions in real time during the cladding process. An algorithm converts these images into robot commands, thereby changing the process parameters in real time during the laser cladding process and ultimately obtaining a tool that meets the usage requirements.

[0078] The present invention, through steps such as tool classification, model simulation, initial parameter setting, and real-time monitoring and adjustment, achieves efficient and high-quality laser cladding repair of tools. This method can adapt to the repair needs of tools of different specifications, reduces experimental verification costs, and improves repair efficiency and quality, thus possessing significant practical application value.

[0079] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for high-speed laser cladding repair of cutting tools based on molten pool morphology, characterized in that, Includes the following steps: Step 1: Classify the cutting tools according to their external dimensions; Step 2: Establish a three-dimensional transient laser cladding mathematical model coupled with temperature and flow field. Predict the relationship between the initial laser cladding process parameters and the molten pool morphology for different types of cutting tools based on the simulation results. In Step 1, the cutting tool classification standards are as follows: Micro-cutting tools: length ≤ 60 mm, thickness ≤ 1 mm; Small cutting tools: length 60-100 mm, thickness 1-1.4 mm; Medium cutting tools: length 100-150 mm, thickness 1.4-1.8 mm; Slightly larger cutting tools: length 150-220 mm, thickness 1.8-2.5 mm; Large cutting tools: length ≥ 220 mm, thickness ≥ 2.5 mm. Step 3: Based on the simulation results of Step 2, initial high-speed laser cladding parameters are determined for different types of cutting tools. The initial high-speed laser cladding parameters for different types of cutting tools in Step 3 are as follows: Micro-cutting tool: laser power 750W, scanning speed 15mm / s, powder feeding speed 1.35g / min; Small cutting tool: laser power 900W, scanning speed 18mm / s, powder feeding speed 1.85g / min; Medium cutting tool: laser power 1100W, scanning speed 22mm / s, powder feeding speed 2.45g / min; Slightly larger cutting tool: laser power 1350W, scanning speed 25mm / s, powder feeding speed 3.20g / min; Large cutting tool: laser power 1500W, scanning speed 30mm / s, powder feeding speed 5.24g / min. Step 4: Based on the initial molten pool morphology of different types of tools, the laser cladding repair parameters are matched in the pre-set laser cladding repair rule library. The molten pool morphology image is captured in real time by the camera installed on the laser cladding head and uploaded to the control terminal for data processing to obtain the molten pool morphology contour. Step 5: The robot drives the laser cladding head to move along the cutting edge of the tool. During the laser cladding process, the laser cladding process parameters are adjusted in real time based on the initial laser cladding parameters according to the morphology of the molten pool, so as to complete the strengthening and repair of the tool.

2. The high-speed laser cladding repair method for cutting tools based on molten pool morphology according to claim 1, characterized in that, In step 2, when establishing a three-dimensional transient laser cladding mathematical model that couples temperature and flow field, the following assumptions were made for the mathematical model to ensure its computational efficiency and accuracy: the initial temperature of laser cladding is defined as 293.15K; both the laser beam and the powder beam follow a Gaussian distribution; the thermal properties of the substrate and cladding layer materials, such as thermal conductivity, specific heat capacity, viscosity, and surface tension, are related to temperature; the influence of the evaporation backpressure caused by the evaporation of the molten pool on the molten pool is ignored; the molten metal in the molten pool is an incompressible Newtonian fluid, and the flow state is laminar.

3. The method for high-speed laser cladding repair of cutting tools based on molten pool morphology according to claim 2, characterized in that, In step 2, the governing equations of the three-dimensional transient laser cladding mathematical model include heat transfer control equations and fluid flow control equations; the heat transfer control equations are: ； In the formula, , ρ, c p k and ρ are the density, specific heat capacity, and thermal conductivity of the material, respectively, and T is the temperature. T is the temperature gradient, u is the velocity field, Q is the laser heat source energy, h is the convective heat transfer coefficient; ε is the material surface emissivity; σ b It is the Steffen-Boltzman constant, which is 5.67E. -8 W / (m 2 ·k 4 );T amb The ambient temperature is 293.15K. The second and third terms on the right side of the formula represent heat convection and heat radiation, respectively. The fluid flow control equations include the Navier-Stokes momentum equation and the continuity equation; Navier-Stokes momentum equation: ; Continuity equation: ; In the formula, P is pressure, I is the unit tensor, and μ is dynamic viscosity. T is the viscosity gradient, and F is the volume force.

4. The high-speed laser cladding repair method for cutting tools based on molten pool morphology according to claim 3, characterized in that, In step 2, the heat transfer boundary conditions during laser cladding include thermal convection and thermal radiation: Thermal convection boundary conditions: ; Thermal radiation boundary conditions: ; In the formula, n is the boundary normal vector and q is the heat flux density.

5. The high-speed laser cladding repair method for cutting tools based on molten pool morphology according to claim 4, characterized in that, In step 2, the mesh generation of the thermal-fluid coupling model is based on the idea of ​​symmetry and only considers half of the model. The region where the molten pool grows is divided into a fine tetrahedral mesh with a maximum element size of 0.286 mm, while the region far from the molten pool is divided into a coarser tetrahedral mesh with a maximum element size of 0.944 mm. The entire model has a total of 23,479 domain elements.

6. The high-speed laser cladding repair method for cutting tools based on molten pool morphology according to claim 1, characterized in that, In steps 4 and 5, the laser cladding repair parameters include cladding powder type, laser power, laser duration, protective gas flow rate, scanning speed, and powder feeding speed.

7. The high-speed laser cladding repair method for cutting tools based on molten pool morphology according to claim 6, characterized in that, The cladding powder types include iron-based alloys, nickel-based alloys, cobalt-based alloys, and graphene / nano-based composite materials; among them, the iron-based alloys are selected from 420 stainless steel or 420+TiC alloy; the nickel-based alloys are selected from Inconel 625, 7-series or 9-series types; and the cobalt-based alloys are ST6+WC type.

8. The high-speed laser cladding repair method for cutting tools based on molten pool morphology according to claim 6, characterized in that, In step 4, a Gaussian surface heat source model is used to simulate the laser heat source, whose energy follows a normal distribution in space.

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