Method and system for detecting current density distribution at the end of an arc welding electrode

Abstract

This invention relates to the field of welding technology, and provides a method and system for detecting the current density distribution at the tip of an arc welding electrode. The method includes the following steps: acquiring image information of the electrode tip region during the welding process; generating a grayscale image based on the image information and acquiring grayscale data of the arc region at the electrode tip; establishing a functional relationship between grayscale values ​​and current density; and obtaining the current density distribution at the electrode tip based on the grayscale data of the arc region at the electrode tip and the functional relationship between grayscale values ​​and current density. The method allows for measurement without contact with the electrode, thus avoiding interference with the welding process. Furthermore, the real-time measurement and extremely fast response speed prevent errors caused by electrode burn-out. The established correspondence between image grayscale values ​​and current density results in relatively accurate results.

Description

Technical Field

[0001] This invention relates to the field of welding technology, and in particular to a method and system for detecting the current density distribution at the tip of an arc welding electrode. Background Technology

[0002] Tungsten inert gas (TIG) welding is an important welding process with wide applications in industrial production. During welding, current density is one of the most crucial parameters, especially the current density distribution on the tungsten electrode surface, which is closely related to the heat input distribution during welding. Obtaining current density distribution data at the tungsten electrode tip is of significant reference value for reducing welding defects and optimizing the welding process.

[0003] Currently, commonly used methods for detecting the current density distribution at the tip of tungsten welding electrodes mainly include the split anode method, ablation trace analysis method, high-speed photography method, and probe method. However, each of these methods has its own shortcomings, either requiring a large amount of calculation or involving cumbersome operation steps. Therefore, there is an urgent need for a simple and fast method for detecting the current density distribution at the tip of arc welding electrodes to solve the technical problems existing in the related technologies. Summary of the Invention

[0004] This invention provides a method for detecting the current density distribution at the end of an arc welding electrode, which solves the technical problem of cumbersome operation steps in the detection of current density distribution at the end of a tungsten electrode in the prior art, and achieves real-time measurement, simple operation and relatively accurate results.

[0005] The present invention also provides a detection system for the current density distribution at the end of an arc welding electrode.

[0006] This invention provides a method for detecting the current density distribution at the tip of an arc welding electrode, comprising the following steps:

[0007] Acquire image information of the electrode tip region during the welding process;

[0008] A grayscale image is generated based on the image information, and grayscale data of the arc region at the electrode end is obtained;

[0009] Establish a functional relationship between grayscale value and current density;

[0010] Based on the grayscale data of the arc region at the electrode end and the functional relationship between the grayscale value and the current density, the distribution of the current density at the electrode end is obtained.

[0011] According to the present invention, a method for detecting the current density distribution at the tip of an arc welding electrode includes the step of acquiring image information of the electrode tip region during the welding process, comprising:

[0012] A charge-coupled device (CCD) camera is used to acquire real-time image information of the electrode end area during the welding process.

[0013] According to the present invention, a method for detecting the current density distribution at the end of an arc welding electrode includes the step of establishing a functional relationship between grayscale value and current density, comprising:

[0014] A first functional relationship is obtained between the number of light-injected charges in the photosensitive unit of the charge-coupled device camera and the photon flux velocity and gray value of the incident light. A second functional relationship is obtained between the photon flux velocity of the incident light and the radiant energy. A third functional relationship is obtained between the radiant energy and the temperature. Based on the first, second and third functional relationships, the functional relationship between the gray value and the temperature is obtained.

[0015] According to the method for detecting the current density distribution at the end of an arc welding electrode provided by the present invention, the step of establishing the functional relationship between grayscale value and current density further includes:

[0016] Obtain the functional relationship between the emission current density at the electrode tip and the temperature. Based on the functional relationship between the gray value and the temperature, obtain the functional relationship between the gray value and the current density.

[0017] According to a method for detecting the current density distribution at the tip of an arc welding electrode provided by the present invention, the step of obtaining the distribution of the current density at the electrode tip based on the functional relationship between the grayscale data of the arc region at the electrode tip and the grayscale value and the current density includes:

[0018] Any pixel at the electrode end in the grayscale image is selected as a standard point. Based on the functional relationship between the grayscale value and temperature, the ratio of physical parameters between the standard point and the other points is obtained. Combined with the functional relationship between the emission current density at the electrode end and temperature, the current density ratio between the standard point and the other points is obtained. The current density ratio between the standard point and the other points is related to the temperature parameter of the standard point.

[0019] According to the present invention, a method for detecting the current density distribution at the tip of an arc welding electrode, the step of obtaining the distribution of the current density at the electrode tip based on the functional relationship between the grayscale data of the arc region at the electrode tip and the grayscale value and the current density, further includes:

[0020] The grayscale image generated by meshing is used to obtain the functional relationship between welding current and unit mesh area. Based on the shape of the electrode end, the expression for the unit mesh area is obtained. Combining the functional relationship between welding current and unit mesh area and the expression for unit mesh area, the functional relationship between welding current and temperature parameters of standard points is obtained. Based on the set value of welding current, the value of temperature parameters of standard points is obtained.

[0021] According to the present invention, a method for detecting the current density distribution at the tip of an arc welding electrode, the step of obtaining the distribution of the current density at the electrode tip based on the functional relationship between the grayscale data of the arc region at the electrode tip and the grayscale value and the current density, further includes:

[0022] Based on the obtained temperature parameters of the standard points, and combined with the current density ratio between the obtained standard points and the other points, the current density of each pixel is obtained.

[0023] According to the present invention, a method for detecting the current density distribution at the end of an arc welding electrode is provided, wherein a narrowband filter and a neutral density filter are arranged in front of the lens of the charge-coupled device camera.

[0024] According to the present invention, a method for detecting the current density distribution at the end of an arc welding electrode is provided, wherein the narrowband filter and the neutral density filter are replaceably mounted in front of the lens of the charge-coupled device camera, wherein at least two narrowband filters are provided, and the spectral lines of the at least two narrowband filters are different, and at least two neutral density filters are provided, and the light reduction ratios of the at least two neutral density filters are different.

[0025] The present invention also provides a detection system for the current density distribution at the tip of an arc welding electrode, comprising:

[0026] Charge-coupled device (CCD) camera, used to acquire image information of the electrode end region during welding;

[0027] A grayscale image generation unit is electrically connected to the charge-coupled device camera and is used to generate a grayscale image based on the image information and acquire grayscale data of the arc region at the electrode end.

[0028] The function relationship establishment unit is electrically connected to the grayscale image generation unit and is used to establish a functional relationship between grayscale values ​​and current density;

[0029] The result output unit is electrically connected to the function relationship establishment unit and is used to obtain the distribution of current density at the electrode end based on the grayscale data of the arc region at the electrode end and the function relationship.

[0030] The method for detecting the current density distribution at the end of an arc welding electrode provided in this invention acquires image information and forms a grayscale image. After establishing a functional relationship between grayscale values ​​and current density, the distribution of current density at the electrode end is directly obtained through the grayscale values ​​of each region. This method allows for measurement without contact with the electrode, thus avoiding any impact on the welding process. Furthermore, based on real-time measurement and extremely fast response speed, it avoids errors caused by electrode burn-out. The method establishes a correspondence between image grayscale values ​​and current density, resulting in relatively accurate results.

[0031] The current density distribution detection system at the end of an arc welding electrode provided in this embodiment of the invention acquires image information and forms a grayscale image. After establishing a functional relationship between grayscale values ​​and current density, the distribution of current density at the end of the electrode is directly obtained through the grayscale values ​​of each region. This method allows for measurement without contact with the electrode, thus avoiding any impact on the welding process. Furthermore, based on real-time measurement and extremely fast response speed, it avoids errors caused by electrode burn-out. The system establishes a correspondence between image grayscale values ​​and current density, resulting in relatively accurate results. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0033] Figure 1 This is a schematic flowchart of the method for detecting the current density distribution at the end of an arc welding electrode provided by the present invention.

[0034] Figure 2 This is a schematic diagram of the structure of the detection system for the current density distribution at the end of the arc welding electrode provided by the present invention;

[0035] Figure 3 This is a schematic diagram of an image acquired from the tungsten end of the device provided by the present invention;

[0036] Figure 4 This is a mesh analysis diagram of the tungsten end portion provided by the present invention;

[0037] Figure 5 This is a curve showing the change in current density of the tungsten end portion as a function of radius, provided by the present invention. Detailed Implementation

[0038] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0039] In the description of the embodiments of the present invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0040] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention based on the specific circumstances.

[0041] In embodiments of the present invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0042] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0043] The following is combined Figures 1-5This invention describes an embodiment of a method for detecting the current density distribution at the tip of an arc welding electrode, comprising the following steps:

[0044] S100: Acquire image information of the electrode end area during the welding process.

[0045] S200: Generate a grayscale image based on the image information and acquire grayscale data of the arc region at the electrode end.

[0046] S300. Establish the functional relationship between grayscale value and current density.

[0047] S400. Based on the grayscale data of the arc region at the electrode end and the functional relationship between grayscale value and current density, the distribution of current density at the electrode end is obtained.

[0048] In this embodiment, by acquiring image information and forming a grayscale image, and establishing a functional relationship between grayscale value and current density, the distribution of current density at the electrode end is directly obtained through the grayscale value of each region. This method allows for measurement without contact with the electrode, thus avoiding any impact on the welding process. Furthermore, based on real-time measurement and extremely fast response speed, it avoids errors caused by electrode burn-out. The established correspondence between image grayscale value and current density yields relatively accurate results.

[0049] The detection method for the current density distribution at the tip of the arc welding electrode is particularly suitable for detecting the current density distribution at the tip of the tungsten electrode in tungsten inert gas (TIG) welding. Based on establishing a quantitative relationship between the arc gray value and the current density distribution at the tip of the tungsten electrode in TIG welding, accurate measured values ​​of the current density at the tip of the tungsten electrode in TIG welding can be obtained.

[0050] Applying the above detection method to the detection of current density distribution at the tungsten electrode tip in tungsten inert gas (TIG) welding has at least the following advantages: 1. It does not directly contact the tungsten electrode and will not affect the welding process; 2. It provides real-time measurement, fast response, avoids errors caused by tungsten electrode burn-out, and is applicable to welding operations with different welding currents; 3. It generates a large amount of data, has low equipment cost, is relatively simple to operate, and can be processed in batches; 4. By establishing a corresponding calculation relationship between image grayscale values ​​and current density, the results obtained are relatively accurate.

[0051] The method for detecting the current density distribution at the tip of an arc welding electrode according to the present invention includes the following steps for acquiring image information of the electrode tip region during welding:

[0052] A charge-coupled device (CCD) camera is used to acquire real-time image information of the electrode end area during the welding process.

[0053] A charge-coupled device camera (CCD camera) is a high-speed camera that uses high-speed cameras to capture images of the electrode area in real time during the welding process, enabling it to respond quickly and achieve real-time detection.

[0054] In this embodiment, the step of establishing the functional relationship between grayscale value and current density includes:

[0055] The first functional relationship between the number of light-injected charges of the photosensitive unit in the charge-coupled device camera and the photon flux of the incident light and the gray value is obtained. The second functional relationship between the photon flux of the incident light and the radiant energy is obtained. The third functional relationship between the radiant energy and the temperature is obtained. Based on the first, second and third functional relationships, the functional relationship between the gray value and the temperature is obtained.

[0056] Specifically, we analyze an infinitesimally small time interval and an infinitesimally small photosensitive unit when the arc stabilizes. The infinitesimally small time interval can be defined as a few milliseconds, and the infinitesimally small photosensitive unit can be defined as a pixel within the capture range. At this point, the first functional relationship between the number of light-injected charges in the photosensitive unit, the photon flux of the incident light, and the grayscale value is as follows:

[0057] Q=ηeΔn eo At = (YB) × G·e;

[0058] Where Q is the photoinjection charge number of the photosensitive unit, η is the quantum efficiency of the material, e is the electron charge, and Δn eo Let η be the photon flux of the incident light, A be the light-receiving area of ​​the photosensitive unit, t be the light injection time (exposure time), Y be the grayscale value (which can be directly generated or read out and is a known quantity in the formula), B be the camera bias value, and G be the camera gain value. For the same charge-coupled device (CCD) camera, η, e, and A are all constants, and the bias value B and gain value G are the same. In this embodiment, the camera bias value B of the CCD camera is 0.131944, and the camera gain value G of the CCD camera is 2.06.

[0059] Specifically, the second function relating the photon flux of the incident light to the radiant energy is as follows:

[0060]

[0061] Θ eλ =Q e ·ΔS;

[0062] Where h is Planck's constant, ν is the frequency of the radiated electromagnetic wave, λ is the wavelength, and Q e It is radiant energy.

[0063] Specifically, the third function relating radiant energy and temperature is as follows:

[0064] Q e =εσT 4 ;

[0065] Among them, Q e Let σ be the radiant energy, ε be the surface emissivity of the object (a constant), and σ be a value that can be 5.67 × 10⁻⁶. -5 Its unit is erg·cm -2 ·K -4 T represents temperature.

[0066] In this embodiment, the step of establishing the functional relationship between grayscale value and current density further includes:

[0067] The functional relationship between the emission current density at the electrode tip and temperature is obtained. Based on the functional relationship between grayscale value and temperature, the functional relationship between grayscale value and current density is obtained.

[0068] Specifically, the functional relationship between the emission current density at the electrode tip and temperature is as follows:

[0069]

[0070] Where j is the current density, C = 60 A / (cm²) 2 ·K 2 T is the temperature, and k is the Boltzmann constant = 8.62 × 10⁻⁶. - 5 ev / K, φ is the work function of the metal, and different values ​​are chosen based on different metals.

[0071] By combining the functional relationship between the emission current density at the electrode tip and temperature with the functional relationship between grayscale value and temperature, the functional relationship between grayscale value and current density can be obtained, establishing the correspondence between image grayscale value and current density, and the obtained results are relatively accurate.

[0072] In this embodiment, the step of obtaining the distribution of current density at the electrode tip based on the functional relationship between grayscale data of the arc region at the electrode tip and grayscale value and current density includes:

[0073] Any pixel at the electrode end in the grayscale image is selected as the standard point. The ratio of physical parameters between the standard point and the other points is obtained based on the functional relationship between grayscale value and temperature. Combined with the functional relationship between the emission current density at the electrode end and temperature, the ratio of current density between the standard point and the other points is obtained. The ratio of current density between the standard point and the other points is related to the temperature parameter of the standard point.

[0074] Define the standard point as point * and the remaining points as point i. Based on the aforementioned functional relationship, the following ratio of physical parameters can be obtained:

[0075]

[0076] The current density ratio between the standard point and the other points is as follows:

[0077]

[0078] In this embodiment, the step of obtaining the distribution of current density at the electrode tip based on the grayscale data of the arc region at the electrode tip and the functional relationship between grayscale value and current density further includes:

[0079] The grayscale image generated by meshing is used to obtain the functional relationship between welding current and unit mesh area. Based on the shape of the electrode end, the expression for unit mesh area is obtained. Combining the functional relationship between welding current and unit mesh area and the expression for unit mesh area, the functional relationship between welding current and temperature parameters of standard points is obtained. Based on the set value of welding current, the value of temperature parameters of standard points is obtained.

[0080] The functional relationship between welding current and element mesh area is as follows:

[0081]

[0082] Where I is the welding current, which will be set to different values ​​based on the actual welding situation. It is a known value. m is the number of grids divided horizontally in the circumferential area of ​​the tungsten end, and n is the number of grids divided vertically in the tungsten end.

[0083] like Figure 3 and Figure 4 As shown, based on the fact that the tungsten end is frustum-shaped, the expression for the element mesh area can be obtained as follows:

[0084]

[0085] Where, ΔS i R is the area of ​​a single cell grid. i For the level of the cell grid, ΔL i The vertical grid spacing is defined for the tungsten end portion.

[0086] In this embodiment, the step of obtaining the distribution of current density at the electrode tip based on the grayscale data of the arc region at the electrode tip and the functional relationship between grayscale value and current density further includes:

[0087] Based on the obtained temperature parameters of the standard points, and combined with the current density ratio between the standard points and other points, the current density of each pixel is obtained.

[0088] Based on the obtained temperature parameter T of the standard point * The value of j can be used to quickly determine the current density j of each of the other pixels through proportional relationships. i This allows for the rapid and accurate determination of the current density at each pixel, thus revealing the distribution of the current density at the electrode tip.

[0089] In this embodiment, a narrowband filter and a neutral density filter are arranged in front of the lens of the charge-coupled device (CCD) camera. The narrowband filter and neutral density filter are replaceably mounted in front of the lens of the CCCD camera. At least two narrowband filters are provided, and the spectral lines of the at least two narrowband filters are different. At least two neutral density filters are provided, and the light reduction ratios of the at least two neutral density filters are different.

[0090] By configuring narrowband filters and neutral density filters, overexposure caused by excessively high temperatures in the arc region can be prevented. Replaceable narrowband filters and neutral density filters allow for adjustments based on different welding conditions. For example, different spectral lines of narrowband filters can be used for different welding currents, and different neutral density filters with different attenuation ratios can be used for different welding currents. Of course, narrowband filters can also employ specific spectral lines to adapt to specific welding conditions.

[0091] On the other hand, such as Figure 2 As shown, this invention also provides a detection system for the current density distribution at the tip of an arc welding electrode, including a charge-coupled device (CCD) camera, a grayscale image generation unit, a function relationship establishment unit, and a result output unit. The CCD camera is used to acquire image information of the electrode tip region during the welding process. The grayscale image generation unit is electrically connected to the CCD camera and is used to generate a grayscale image based on the image information and acquire grayscale data of the arc region at the electrode tip. The function relationship establishment unit is electrically connected to the grayscale image generation unit and is used to establish a functional relationship between grayscale values ​​and current density. The result output unit is electrically connected to the function relationship establishment unit and is used to obtain the current density distribution at the electrode tip based on the grayscale data of the arc region at the electrode tip and the functional relationship.

[0092] In this embodiment, by acquiring image information and forming a grayscale image, and establishing a functional relationship between grayscale value and current density, the distribution of current density at the electrode end is directly obtained through the grayscale value of each region. This method allows for measurement without contact with the electrode, thus avoiding any impact on the welding process. Furthermore, based on real-time measurement and extremely fast response speed, it avoids errors caused by electrode burn-out. The established correspondence between image grayscale value and current density yields relatively accurate results.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for detecting the current density distribution at the tip of an arc welding electrode, characterized in that, Includes the following steps: Acquire image information of the electrode tip region during the welding process; A grayscale image is generated based on the image information, and grayscale data of the arc region at the electrode end is obtained; Establish a functional relationship between grayscale value and current density; Based on the functional relationship between the grayscale data of the arc region at the electrode tip and the grayscale value and current density, the distribution of the current density at the electrode tip is obtained. The step of establishing the functional relationship between grayscale value and current density includes: A first functional relationship is obtained between the number of light-injected charges of the photosensitive unit in the charge-coupled device camera and the photon flux velocity and gray value of the incident light; a second functional relationship is obtained between the photon flux velocity of the incident light and the radiant energy; a third functional relationship is obtained between the radiant energy and the temperature; and based on the first functional relationship, the second functional relationship, and the third functional relationship, the functional relationship between the gray value and the temperature is obtained. The first functional relationship between the number of light-injected charges in the photosensitive unit, the photon flux of the incident light, and the gray value is as follows: ； in, The number of light-injected charges for the photosensitive unit, For the quantum efficiency of materials, The amount of electron charge. The photon flux of the incident light. The light-receiving area of ​​the photosensitive unit. Inject time into light, Grayscale value This is the camera offset value. This is the camera gain value; The second function relating the photon flux of incident light to radiant energy is as follows: ； ； in, Let be Planck's constant. The frequency of the radiated electromagnetic wave, For wavelength, For radiation flux, It is radiant energy; The area of ​​a single grid cell; The third function relating radiant energy and temperature is as follows: ； in, As radiant energy, The surface emissivity of the object is a constant. The value is 5.67 × 10⁻⁵, and its unit is erg·cm⁻²·K⁻⁴. For temperature; The step of establishing the functional relationship between grayscale value and current density further includes: Obtain the functional relationship between the emission current density at the electrode tip and the temperature; based on the functional relationship between the gray value and the temperature, obtain the functional relationship between the gray value and the current density. The functional relationship between the emission current density at the electrode tip and temperature is as follows: ； in, For current density, =60A / (cm2·K2), For temperature, Boltzmann constant = 8.62 × 10⁻⁵ eV / K It is the work function of metal; The step of obtaining the distribution of current density at the electrode tip based on the functional relationship between the grayscale data of the arc region at the electrode tip and the grayscale value and current density includes: Select any pixel at the electrode end in the grayscale image as a standard point. Based on the functional relationship between the grayscale value and temperature, obtain the ratio of physical parameters between the standard point and the other points. Combined with the functional relationship between the emission current density at the electrode end and temperature, obtain the current density ratio between the standard point and the other points. The current density ratio between the standard point and the other points is related to the temperature parameter of the standard point. Define the standard point as Point, define the remaining points as Based on the aforementioned functional relationship, the following ratio of physical parameters can be obtained: ； in, The number of light-injected charges for any photosensitive cell corresponding to any grid cell in the image. This represents the number of light-injected charges in the photosensitive cell corresponding to the cell grid where the standard point is located. This represents the grayscale value of any cell in the image. The grayscale value of the cell grid containing the standard point. Let the photon flux of the incident light be any cell in the image. The photon flux of the incident light in the cell grid where the standard point is located. Let be the radiant flux of any cell in the image grid. This represents the radiative flux of the cell containing the standard point. Let be the radiant energy of any cell grid in the image. The radiant energy of the cell grid where the standard point is located. The area of ​​any cell in the image grid. The area of ​​the cell containing the standard point. The temperature of any cell in the image. The temperature of the cell containing the standard point; the current density ratio between the standard point and the other points is as follows: ； in, The current density of any cell grid in the image. The current density of the cell grid where the standard point is located; The step of obtaining the distribution of current density at the electrode tip based on the functional relationship between the grayscale data of the arc region at the electrode tip and the grayscale value and current density further includes: The grayscale image generated by meshing is used to obtain the functional relationship between welding current and unit mesh area. Based on the shape of the electrode end, the expression of unit mesh area is obtained. Combining the functional relationship between welding current and unit mesh area and the expression of unit mesh area, the functional relationship between welding current and temperature parameter of standard point is obtained. Based on the set value of welding current, the value of temperature parameter of standard point is obtained. The functional relationship between welding current and element mesh area is as follows: ； in, This refers to the welding current. Different welding current values ​​will be set based on actual welding conditions; these are known values. The number of grids horizontally divided in the circumferential region of the tungsten end. The number of grids is determined for the longitudinal division of the tungsten end portion.

2. The method for detecting the current density distribution at the end of an arc welding electrode according to claim 1, characterized in that, The step of acquiring image information of the electrode end region during the welding process includes: A charge-coupled device (CCD) camera is used to acquire real-time image information of the electrode end area during the welding process.

3. The method for detecting the current density distribution at the end of an arc welding electrode according to claim 2, characterized in that, The step of obtaining the distribution of current density at the electrode tip based on the functional relationship between the grayscale data of the arc region at the electrode tip and the grayscale value and current density further includes: Based on the obtained temperature parameters of the standard points, and combined with the current density ratio between the obtained standard points and the other points, the current density of each pixel is obtained.

4. The method for detecting the current density distribution at the end of an arc welding electrode according to any one of claims 2-3, characterized in that, The charge-coupled device (CCD) camera has a narrowband filter and a neutral density filter arranged in front of the lens.

5. The method for detecting the current density distribution at the end of an arc welding electrode according to claim 4, characterized in that, The narrowband filter and the neutral density filter are replaceably mounted in front of the lens of the charge-coupled device camera. The narrowband filter is configured to be at least two, and the spectral lines of the at least two narrowband filters are different. The neutral density filter is configured to be at least two, and the light reduction ratio of the at least two neutral density filters is different.

6. A detection system for the current density distribution at the tip of an arc welding electrode, characterized in that, include: Charge-coupled device (CCD) camera, used to acquire image information of the electrode end region during welding; A grayscale image generation unit is electrically connected to the charge-coupled device camera and is used to generate a grayscale image based on the image information and acquire grayscale data of the arc region at the electrode end. The function relationship establishment unit is electrically connected to the grayscale image generation unit and is used to establish a functional relationship between grayscale values ​​and current density; The result output unit is electrically connected to the function relationship establishment unit and is used to obtain the distribution of current density at the electrode end based on the grayscale data of the arc region at the electrode end and the function relationship. The step of establishing the functional relationship between grayscale value and current density includes: A first functional relationship is obtained between the number of light-injected charges of the photosensitive unit in the charge-coupled device camera and the photon flux velocity and gray value of the incident light; a second functional relationship is obtained between the photon flux velocity of the incident light and the radiant energy; a third functional relationship is obtained between the radiant energy and the temperature; and based on the first functional relationship, the second functional relationship, and the third functional relationship, the functional relationship between the gray value and the temperature is obtained. The first functional relationship between the number of light-injected charges in the photosensitive unit, the photon flux of the incident light, and the gray value is as follows: ； in, The number of light-injected charges for the photosensitive unit, For the quantum efficiency of materials, The amount of electron charge. The photon flux of the incident light. The light-receiving area of ​​the photosensitive unit. Light injection time (exposure time). Grayscale value This is the camera offset value. This is the camera gain value; The second function relating the photon flux of incident light to radiant energy is as follows: ； ； in, Let be Planck's constant. The frequency of the radiated electromagnetic wave, For wavelength, For radiation flux, It is radiant energy; The area of ​​a single grid cell; The third function relating radiant energy and temperature is as follows: ； in, As radiant energy, The surface emissivity of the object is a constant. The value is 5.67 × 10⁻⁵, and its unit is erg·cm⁻²·K⁻⁴. For temperature; The step of establishing the functional relationship between grayscale value and current density further includes: Obtain the functional relationship between the emission current density at the electrode tip and the temperature; based on the functional relationship between the gray value and the temperature, obtain the functional relationship between the gray value and the current density. The functional relationship between the emission current density at the electrode tip and temperature is as follows: ； in, For current density, =60A / (cm2·K2), For temperature, Boltzmann constant = 8.62 × 10⁻⁵ eV / K It is the work function of metal; The step of obtaining the distribution of current density at the electrode tip based on the functional relationship between the grayscale data of the arc region at the electrode tip and the grayscale value and current density includes: Select any pixel at the electrode end in the grayscale image as a standard point. Based on the functional relationship between the grayscale value and temperature, obtain the ratio of physical parameters between the standard point and the other points. Combined with the functional relationship between the emission current density at the electrode end and temperature, obtain the current density ratio between the standard point and the other points. The current density ratio between the standard point and the other points is related to the temperature parameter of the standard point. Define the standard point as Point, define the remaining points as Based on the aforementioned functional relationship, the following ratio of physical parameters can be obtained: ； in, The number of light-injected charges for any photosensitive cell corresponding to any grid cell in the image. This represents the number of light-injected charges in the photosensitive cell corresponding to the cell grid where the standard point is located. This represents the grayscale value of any cell in the image. The grayscale value of the cell grid containing the standard point. Let the photon flux of the incident light be any cell in the image. The photon flux of the incident light in the cell grid where the standard point is located. Let be the radiant flux of any cell in the image grid. This represents the radiative flux of the cell containing the standard point. Let be the radiant energy of any cell grid in the image. The radiant energy of the cell grid where the standard point is located. The area of ​​any cell in the image grid. The area of ​​the cell containing the standard point. The temperature of any cell in the image. The temperature of the cell grid where the standard point is located; The current density ratio between the standard point and the other points is as follows: ； in, The current density of any cell grid in the image. The current density of the cell grid where the standard point is located; The step of obtaining the distribution of current density at the electrode tip based on the functional relationship between the grayscale data of the arc region at the electrode tip and the grayscale value and current density further includes: The grayscale image generated by meshing is used to obtain the functional relationship between welding current and unit mesh area. Based on the shape of the electrode end, the expression of unit mesh area is obtained. Combining the functional relationship between welding current and unit mesh area and the expression of unit mesh area, the functional relationship between welding current and temperature parameter of standard point is obtained. Based on the set value of welding current, the value of temperature parameter of standard point is obtained. The functional relationship between welding current and element mesh area is as follows: ； in, This refers to the welding current. Different welding current values ​​will be set based on actual welding conditions; these are known values. The number of grids horizontally divided in the circumferential region of the tungsten end. The number of grids is determined for the longitudinal division of the tungsten end portion.

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