Evaluation method for welding wire feeding stability

Abstract

The invention discloses a method for evaluating welding wire feeding stability, which comprises the following steps of: measuring the frictional resistance of a welding wire at a set position in a welding process, and collecting the change of the frictional resistance of the welding wire at the set position in the welding process; measuring the real-time coordinates of the welding wire center point on the set plane when the welding wire dry extends in the welding process; based on the real-time coordinates, the eccentric distance of the center point of the welding wire and the change of the eccentric distance are obtained; obtaining an azimuth angle formed by a connecting line of the welding wire center and the welding gun center and the positive welding direction and the change of the azimuth angle based on the real-time coordinates; and evaluating the wire feeding stability in the welding process based on the change of the frictional resistance, the change of the eccentric distance and the change of the azimuth angle. According to the method, not only is the detection of the axial feeding stability improved, but also the evaluation technology of the spatial position of the end part of the welding wire is supplemented, so that the evaluation method is more comprehensive and accurate. Meanwhile, the method is convenient to install and operate and has high generalizability.

Description

Technical Field

[0001] The present invention relates to an evaluation method, in particular to an evaluation method for welding performance. Background Art

[0002] In the welding process of metal arc welding and submerged arc welding, since the welding wire itself acts as an electrode to generate an arc, the wire feeding stability is very important for the welding quality. The wire feeding stability of the welding wire should include two aspects:

[0003] On the one hand, there is stability or uniformity in the feeding direction, and some prior arts have attempted to provide solutions to this problem.

[0004] For example, a Chinese patent document entitled "A Method for Evaluating the Stability of Welding Wire Feeding Speed" with publication number CN108098120A and publication date June 1, 2018, proposes a method for evaluating the stability of welding wire feeding speed. The method uses a component of a laser diffuse reflection sensor, a counting / timing card, a computer, and a laser reflection grating sticker to convert the evaluation of wire feeding speed stability into a measurement of the rotation speed of the wire feeding wheel and the straightening wheel, thereby achieving a quantitative evaluation of the stability of the welding wire feeding speed. This method is easy to implement and simple to install, but it is a method for measuring the uniformity of wire feeding speed.

[0005] In terms of design principle, this method counts and converts time by sticking stickers on the wire feed wheel and the straightening wheel. However, since the laser stickers themselves occupy a certain volume, their sticking density is limited, which results in the sampling frequency (i.e., measurement accuracy) of this method being limited. Moreover, when the surface state of the welding wire changes, especially when the welding wire is contaminated by oil or rust, its measured value may not truly reflect the actual wire feed speed. For example, when there is oil on the surface of the welding wire, the wire will slip, and the actual wire feed speed has decreased, but the wire feed wheel may still be rotating, and the wire feed speed can still be obtained.

[0006] It can be seen that this stability detection method only considers the stability of the welding wire in the feeding direction, but fails to consider the impact of the change in the spatial position of the welding wire on welding.

[0007] Another aspect of wire feeding stability is the spatial position stability of the wire end. Under certain welding conditions, such as in a workpiece with a groove, the height of the surface to be welded is different. At this time, the constant change in the relative position of the wire end will cause the distance between the wire end and the workpiece surface to be welded to change continuously, thereby causing fluctuations in welding voltage and current, affecting welding stability. The physical performance indicators of the wire itself, such as relaxation diameter and warpage, currently specified in engineering (national standard GB / T8110-2020 "Solid welding wire of non-alloy steel and fine-grained steel for gas shielded arc welding") and the tensile strength of the wire itself can reflect the feeding stability of the wire to a certain extent, but the judgment based on such indicators is very indirect and requires very rich engineering experience.

[0008] It can be seen that the wire feeding stability detection technical solution in the current prior art is mainly aimed at the uniformity detection of the wire feeding speed, which lacks comprehensiveness and does not consider the impact of the spatial position change of the welding wire end on welding. In some cases, the detection of the actual wire feeding speed may be inaccurate. Summary of the invention

[0009] The purpose of the present invention is to provide a method for evaluating the stability of welding wire feeding, which reflects the wire feeding stability of the welding wire during the welding process through three indicators: friction resistance, eccentricity and azimuth, thereby providing a comprehensive and accurate technical evaluation scheme for the stability detection of welding wire feeding.

[0010] In order to achieve the above object, the present invention provides a method for evaluating welding wire feeding stability, which comprises the steps of:

[0011] Measure the friction resistance of the welding wire at the set position during welding, and collect the change of the friction resistance of the welding wire at the set position during welding;

[0012] Measure the real-time coordinates of the center point of the welding wire on the set plane during welding;

[0013] Obtaining the eccentricity of the center point of the welding wire and the change of the eccentricity based on the real-time coordinates;

[0014] Based on the real-time coordinates, the azimuth angle formed by the line connecting the center of the welding wire and the center of the welding gun and the positive welding direction and the change of the azimuth angle are obtained;

[0015] Based on the changes in the friction resistance, the eccentricity and the azimuth, the wire feeding stability during the welding process is evaluated.

[0016] The evaluation method for welding wire feeding stability described in the present invention measures the axial wire feeding stability during welding wire feeding by measuring the friction resistance; measures the radial wire feeding stability during welding by measuring the change in the eccentricity of the welding wire center relative to the welding gun center on a set plane of the welding wire dry extension; measures the circumferential wire feeding stability during welding by the change in the azimuth angle between the welding wire center-welding gun center connection line and the welding positive direction on the welding wire dry extension setting plane; and finally reflects the wire feeding stability of the welding wire during welding by using three indicators of friction resistance (characterizing the axial direction), eccentricity (characterizing the radial direction), and azimuth (characterizing the circumferential direction), thereby providing a comprehensive and accurate technical evaluation scheme for the detection of welding wire feeding stability.

[0017] Furthermore, in the evaluation method of welding wire feeding stability described in the present invention, measuring and collecting the friction resistance of the welding wire at a set fixed position during welding includes the steps of:

[0018] An annular force sensor is installed upstream of the wire feeding wheel to measure the friction resistance encountered by the welding wire when it passes through the set position of the annular force sensor.

[0019] In some embodiments, an annular force sensor can be installed upstream of the wire feeding wheel to measure the change in friction resistance encountered by the welding wire when passing through the fixed position of the sensor, so as to qualitatively reflect the fluctuation of axial wire feeding stability caused by the change of the welding wire's own state information.

[0020] Furthermore, in the evaluation method for welding wire feeding stability of the present invention, measuring the real-time coordinates of the center point of the welding wire on the set plane during welding includes the following steps:

[0021] The micrometer system is used to measure the real-time coordinates (x, y) of the center point of the welding wire on the set plane, where the welding starting point is the coordinate origin and the welding direction is the positive direction of the y-axis.

[0022] Furthermore, in the evaluation method of welding wire feeding stability of the present invention, the eccentricity D of the center point of the welding wire is obtained based on the real-time coordinates using the following formula:

[0023] D=(x 2 +|yv×t| 2 ) 1 / 2 ;

[0024] Where (x, y) represents the real-time coordinates of the center point of the welding wire, v represents the welding speed, and the unit parameter is mm / s; t represents the welding time, and the unit parameter is s.

[0025] In some embodiments, the real-time coordinate data x and y of the center point of the welding wire on a certain plane of the wire elongation can be measured by a high-precision micrometer system installed in the welding direction (the measurement coordinate system satisfies the right-hand rule, where the welding starting point is the coordinate origin and the welding direction is the positive direction of the y-axis), and the change in the eccentricity D of the real-time center of the welding wire relative to the center of the welding gun is converted to measure the radial stability of the end of the welding wire.

[0026] Further, in the evaluation method of welding wire feeding stability described in the present invention, obtaining the azimuth angle θ (0°≤θ﹤360°) formed by the line connecting the center of the welding wire and the center of the welding gun and the positive direction of welding based on the real-time coordinates includes the steps of: determining the azimuth angle θ based on the following formula:

[0027] θ = acrtan(x / (y-vt))-90°;

[0028] in:

[0029] When y-vt>0 and x≤0, 0°≤θ﹤90°;

[0030] When y-vt=0 and x<0, θ=90°;

[0031] When y-vt<0 and x≤0, 90°﹤θ≤180°;

[0032] When y-vt<0 and x﹥0, 180°﹤θ﹤270°;

[0033] When y-vt=0 and x>0, θ=270°;

[0034] When y-vt>0 and x>0, 270°<θ<360°;

[0035] Where (x, y) represents the real-time coordinates of the center point of the welding wire, v represents the welding speed, and the unit parameter is mm / s, and t represents the welding time, and the unit parameter is s.

[0036] In some embodiments, a high-precision micrometer system can be installed in the welding direction to measure online the real-time coordinate data x and y of the center point of the welding wire on a certain plane of the welding wire dry extension, and the angle θ between the line connecting the real-time center of the welding wire and the center of the welding gun (i.e., the theoretical center of the welding wire) and the positive direction of welding can be obtained by converting it, and this is used as the azimuth angle to reflect the spatial position change of the vertex of the end of the welding wire and measure the circumferential stability of the end of the welding wire.

[0037] Further, in the evaluation method of welding wire feeding stability of the present invention, based on the change of the friction resistance, the change of the eccentricity and the change of the azimuth, evaluating the wire feeding stability during the welding process includes the steps of:

[0038] The standard deviation of friction resistance is obtained based on the change of friction resistance, the standard deviation of eccentricity is obtained based on the change of eccentricity, and the standard deviation of azimuth is obtained based on the change of azimuth;

[0039] When the standard deviation of friction resistance σ≤0.5, the standard deviation of eccentricity σ≤0.2, and the standard deviation of azimuth angle σ≤5, the wire feeding stability of the welding wire is judged to be excellent.

[0040] Further, in the evaluation method of welding wire feeding stability of the present invention, based on the change of the friction resistance, the change of the eccentricity and the change of the azimuth, evaluating the wire feeding stability during the welding process includes the steps of:

[0041] The standard deviation of friction resistance is obtained based on the change of friction resistance, the standard deviation of eccentricity is obtained based on the change of eccentricity, and the standard deviation of azimuth is obtained based on the change of azimuth;

[0042] The wire feeding stability of the welding wire is judged to be good when at least one of the following conditions is met:

[0043] Friction resistance standard deviation 0.5<σ≤3;

[0044] Standard deviation of eccentricity 0.2<σ≤0.5;

[0045] The standard deviation of the azimuth angle is 5≤σ≤10.

[0046] Further, in the evaluation method of welding wire feeding stability of the present invention, based on the change of the friction resistance, the change of the eccentricity and the change of the azimuth, evaluating the wire feeding stability during the welding process includes the steps of:

[0047] The standard deviation of friction resistance is obtained based on the change of friction resistance, the standard deviation of eccentricity is obtained based on the change of eccentricity, and the standard deviation of azimuth is obtained based on the change of azimuth;

[0048] When at least one of the following conditions is met, the wire feeding stability of the welding wire is judged to be poor:

[0049] Friction resistance standard deviation σ>3;

[0050] The standard deviation of eccentricity σ>0.5;

[0051] The azimuth standard deviation σ>10.

[0052] The evaluation method of welding wire feeding stability of the present invention has the following advantages and beneficial effects compared with the prior art:

[0053] The evaluation method of the present invention can evaluate the feeding stability of the welding wire during welding by three indicators: friction resistance (axial), eccentricity (radial), and azimuth (circumferential). Compared with the prior art, not only the detection of axial feeding stability is improved, but also the technical means for evaluating the spatial position of the welding wire end are supplemented, and the evaluation method is more comprehensive and accurate.

[0054] In addition, the evaluation method of the present invention requires simple equipment, is easy to install, and is convenient to operate, and has high scalability. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 The structural diagram of the implementation system of the welding wire feeding stability evaluation method of the present invention is schematically shown.

[0056] Figure 2 The test results of the friction resistance change of Example 1 of the evaluation method of welding wire feeding stability according to the present invention are shown.

[0057] Figure 3 The test results of the eccentricity change of Example 1 of the evaluation method for welding wire feeding stability according to the present invention are shown.

[0058] Figure 4 The test results of the azimuth angle change of Example 1 using the evaluation method for welding wire feeding stability of the present invention are shown.

[0059] Figure 5 The results of detecting the change in friction resistance of Example 2 of the method for evaluating welding wire feeding stability according to the present invention are shown.

[0060] Figure 6 The test results of the eccentricity and its change of Example 2 of the evaluation method of welding wire feeding stability described in the present invention are shown.

[0061] Figure 7 The test results of the azimuth angle change of Example 2 of the evaluation method for welding wire feeding stability described in the present invention are shown.

[0062] Figure 8 The test results of the friction resistance change of Example 3 of the evaluation method of welding wire feeding stability according to the present invention are shown.

[0063] Fig. 9 The test results of the eccentricity change of Example 3 of the evaluation method of welding wire feeding stability described in the present invention are shown.

[0064] Fig.10 The test results of the azimuth angle change of Example 3 of the evaluation method for welding wire feeding stability described in the present invention are shown. DETAILED DESCRIPTION

[0065] The evaluation method for welding wire feeding stability of the present invention will be further explained and illustrated below in conjunction with specific embodiments and the accompanying drawings of the specification. However, such explanation and illustration do not constitute an improper limitation on the technical solution of the present invention.

[0066] Figure 1 The structural diagram of the implementation system of the welding wire feeding stability evaluation method of the present invention is schematically shown.

[0067] like Figure 1 As shown, in some embodiments, the evaluation method described in the present invention can be implemented using the implementation system, which includes: a welding gun 1 for implementing welding, a wire feeding wheel and a clamping wheel 2 for conveying a welding wire 3, the front end of the welding wire 3 is a welding wire dry extension 4, the welding gun 1 welds a welding test plate 6 placed on a welding platform 7 to obtain a welding molten pool 5, the welding gun 1 is connected to a welding power supply 8, an annular force sensor 9 is sleeved on the periphery of the welding wire and is arranged upstream of the wire feeding wheel, a micrometer system, which includes a laser generator 10, a micrometer laser receiver 11, an optical filtering system 12, a micrometer optical path 13, a signal acquisition and recording system 14, collects data sent to it by the micrometer laser receiver 11 and the annular force sensor 9, and sends these data to a computer 15 for analysis and processing.

[0068] In some embodiments, a method for evaluating welding wire feeding stability may include the steps of:

[0069] 100: using an annular force sensor 9 to measure the friction resistance of the welding wire 3 at a set position during welding, and using a signal acquisition and recording system 14 to collect changes in the friction resistance of the welding wire at the set position during welding, and sending it to a computer 15;

[0070] By installing an annular force sensor upstream of the wire feeding wheel, the change in friction resistance encountered by the welding wire when it passes through the fixed position of the sensor is measured, so as to qualitatively reflect the fluctuation of axial wire feeding stability caused by changes in the welding wire's own state information.

[0071] 200: The real-time coordinates (x, y) of the center point of the welding wire on the set plane during welding are measured by a micrometer system, wherein the welding starting point is the coordinate origin and the welding direction is the positive direction of the y axis. The real-time coordinate data x is perpendicular to the welding direction and y is parallel to the welding direction.

[0072] 300: Obtaining the eccentricity D of the center point of the welding wire and the change of the eccentricity based on the real-time coordinates (x, y);

[0073] In some more specific embodiments, the eccentricity D of the center point of the welding wire can be obtained by using the following formula:

[0074] D=(x 2 +|yv×t| 2 ) 1 / 2 .

[0075] In this embodiment, the real-time coordinate data x and y of the center point of the welding wire on a certain plane of the wire elongation are measured by a high-precision micrometer system installed in the welding direction (the measurement coordinate system satisfies the right-hand rule, where the welding starting point is the coordinate origin and the welding direction is the positive direction of the y-axis), and the change in the eccentricity D of the real-time center of the welding wire relative to the center of the welding gun is converted to measure the radial stability of the end of the welding wire.

[0076] 400: based on the real-time coordinates (x, y), obtain the azimuth angle formed by the line connecting the center of the welding wire and the center of the welding gun and the positive welding direction, and the change of the azimuth angle;

[0077] In some more specific implementations, the following formula may be used to obtain the azimuth angle θ (0°≤θ﹤360°) formed by the line connecting the center of the welding wire and the center of the welding gun and the positive welding direction:

[0078] θ=acrtan(x / (y-vt))-90°; where:

[0079] When y-vt>0 and x≤0, 0°≤θ﹤90°;

[0080] When y-vt=0 and x<0, θ=90°;

[0081] When y-vt<0 and x≤0, 90°﹤θ≤180°;

[0082] When y-vt<0 and x﹥0, 180°﹤θ﹤270°;

[0083] When y-vt=0 and x>0, θ=270°;

[0084] When y-vt﹥0 and x>0, 270°﹤θ﹤360°.

[0085] By installing a high-precision micrometer system in the welding direction, the real-time coordinate data x and y of the center point of the welding wire on a certain plane of the welding wire extension are measured online, and the angle θ between the line connecting the real-time center of the welding wire and the center of the welding gun (i.e. the theoretical center of the welding wire) and the positive direction of welding is obtained by conversion, and this is used as the azimuth, which can reflect the spatial position change of the vertex of the end of the welding wire and measure the circumferential stability of the end of the welding wire.

[0086] 500: Evaluate wire feeding stability during welding based on changes in friction resistance, eccentricity, and azimuth.

[0087] In some more specific embodiments, when the standard deviation of the friction resistance σ≤0.5, the standard deviation of the eccentricity σ≤0.2, and the standard deviation of the azimuth angle σ≤5, the wire feeding stability of the welding wire is determined to be excellent.

[0088] The wire feeding stability of the welding wire is judged to be good when at least one of the following conditions is met:

[0089] Friction resistance standard deviation 0.5<σ≤3;

[0090] Standard deviation of eccentricity 0.2<σ≤0.5;

[0091] Azimuth standard deviation 5≤σ≤10;

[0092] When at least one of the following conditions is met, the wire feeding stability of the welding wire is judged to be poor:

[0093] Friction resistance standard deviation σ>3;

[0094] The standard deviation of eccentricity σ>0.5;

[0095] The azimuth standard deviation σ>10.

[0096] The standard deviation σ is calculated using the following formula:

[0097]

[0098] Where σ represents the standard deviation of the data of friction resistance, eccentricity and azimuth, x i It represents the real-time data of friction resistance, eccentricity and azimuth collected during the sampling period, and n represents the total number of data collected. It represents the average value of all the collected friction resistance, eccentricity and azimuth data, and i is an integer from 1 to n.

[0099] In order to further reflect the technical effect of the preferred implementation mode of this case, the present invention adopts the same submerged arc welding machine and selects three welding wires with the same strength level but different compositions (ie, Example 1, Example 2, and Example 3) for flat plate surfacing to compare their wire feeding stability.

[0100] In Examples 1-3, the length of the welding test plate 6 in the welding direction can be 160 mm, the diameter of the welding wire 3 is controlled to be 4 mm, and the length of the welding wire extension 4 can be controlled to be 15 mm. During welding, the welding parameters of the three welding wires are the same, wherein the welding current can be controlled to be 500 A, the welding voltage can be controlled to be 28 V, the welding speed can be controlled to be 480 mm / min, and the shielding gas flow rate can be controlled to be 20 L / min.

[0101] In Examples 1-3, Figure 1As shown, a micrometer laser generator 10, a micrometer laser receiver 11, a signal acquisition and recording system 14 and a computer 15 can be arranged perpendicular to the plane of the wire extension. The measuring direction of the micrometer system is consistent with the welding direction, and the measuring center is consistent with the weld center. The micrometer laser generator 10 and the micrometer laser receiver 11 are respectively fixed at the head and tail of the welding test plate 6, so that the length of the micrometer optical path 13 is consistent with the welding length. More specifically, the sampling frequency of the micrometer laser receiver 11 can be controlled to 100HZ, and the optical filter system 12 can use a light-reducing film with a transmittance of 50%.

[0102] After calibrating the micrometer system and turning on the signal acquisition and recording system 14, the flat plate surfacing experiment can be started for three welding wires (i.e., Example 1, Example 2, and Example 3). Further, the detection time (i.e., welding duration) can be controlled to 20s, and the real-time coordinate data (x, y) of the friction resistance and the center of the welding wire can be obtained. The computer 15 processes and converts the eccentricity change of the welding wire center relative to the welding gun center (i.e., the eccentricity spectrum), and the azimuth angle θ change diagram of the welding wire center-welding gun center line and the welding positive direction.

[0103] Figure 2 , Figure 3 and Figure 4 The test results of friction resistance, eccentricity and azimuth change of Example 1 are shown respectively. The horizontal axis in the figure is the test time, that is, the whole welding process; the vertical axis is from Figure 2-Figure 4 where represent friction resistance, eccentricity and azimuth respectively.

[0104] from Figure 2 , Figure 3 and Figure 4 It can be seen that in Example 1, during the welding process, the friction resistance, eccentricity and azimuth angle fluctuate greatly, with standard deviations of 3.3, 0.6 and 10.2 respectively. According to the determination and evaluation indicators of the present invention, the wire feeding stability is determined to be poor.

[0105] Figure 5 , Figure 6 and Figure 7 The test results of friction resistance, eccentricity and azimuth change of Example 2 are shown respectively. The horizontal axis in the figure is the test time, that is, the whole welding process; the vertical axis is from Figure 5-Figure 7 where represent friction resistance, eccentricity and azimuth respectively.

[0106] from Figure 5 , Figure 6 and Figure 7 It can be seen that in Example 2, during the welding process, the standard deviations of the friction resistance, eccentricity and azimuth are 1.4, 0.4 and 3.9 respectively. According to the determination and evaluation indexes of the present invention, the wire feeding stability is determined to be good.

[0107] Figure 8 , Fig. 9 and Fig.10 The test results of friction resistance, eccentricity and azimuth change of Example 3 are shown respectively. The horizontal axis in the figure is the test time, that is, the whole welding process; the vertical axis is from Figure 8-Figure 10 where represent friction resistance, eccentricity and azimuth respectively.

[0108] from Figure 8 , Fig. 9 and Fig.10 It can be seen that in Example 3, during the welding process, the friction resistance, eccentricity and azimuth angle change very little, with standard deviations of 0.3, 0.1 and 1.8 respectively. According to the determination and evaluation indicators of the present invention, the wire feeding stability is determined to be excellent.

[0109] It should be noted that the combination of the various technical features in this case is not limited to the combination described in the claims of this case or the combination described in the specific embodiments. All technical features recorded in this case can be freely combined or combined in any way unless there is a contradiction between them.

[0110] It should also be noted that the above-listed embodiments are only specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and similar changes or modifications made therewith can be directly derived or easily associated with the contents disclosed by those skilled in the art from the present invention, and all should belong to the protection scope of the present invention.

Claims

1. A method for evaluating welding wire feeding stability, characterized in that: Includes steps: Measure the friction resistance of the welding wire at the set position during welding, and collect the change of the friction resistance of the welding wire at the set position during welding; Measure the real-time coordinates of the center point of the welding wire on the set plane during welding; Obtaining the eccentricity of the center point of the welding wire and the change of the eccentricity based on the real-time coordinates; Based on the real-time coordinates, the azimuth angle formed by the line connecting the center of the welding wire and the center of the welding gun and the positive welding direction and the change of the azimuth angle are obtained; Based on the changes in the friction resistance, the eccentricity and the azimuth, the wire feeding stability during the welding process is evaluated.

2. The method for evaluating welding wire feeding stability according to claim 1, characterized in that: Measuring and collecting the friction resistance of the welding wire at a set fixed position during welding includes the following steps: An annular force sensor is installed upstream of the wire feeding wheel to measure the friction resistance encountered by the welding wire when it passes through the set position of the annular force sensor.

3. The method for evaluating welding wire feeding stability according to claim 1, characterized in that: Measuring the real-time coordinates of the center point of the welding wire on the set plane during welding includes the following steps: The micrometer system is used to measure the real-time coordinates (x, y) of the center point of the welding wire on the set plane, where the welding starting point is the coordinate origin and the welding direction is the positive direction of the y-axis.

4. The method for evaluating welding wire feeding stability according to claim 1, characterized in that: Based on the real-time coordinates, the eccentricity D of the center point of the welding wire is obtained by the following formula: D=(x 2 +|y-v×t| 2 ) 1 / 2 ; Where (x, y) represents the real-time coordinates of the center point of the welding wire, v represents the welding speed, and the unit parameter is mm / s, and t represents the welding time, and the unit parameter is s.

5. The method for evaluating welding wire feeding stability according to claim 1, characterized in that: Obtaining the azimuth angle θ formed by the line connecting the center of the welding wire and the center of the welding gun and the positive welding direction based on the real-time coordinates includes the following steps: determining the azimuth angle θ based on the following formula: θ=acrtan(x / (y-vt))-90°; where: When y-vt>0 and x≤0, 0°≤θ﹤90°; When y-vt=0 and x<0, θ=90°; When y-vt<0 and x≤0, 90°﹤θ≤180°; When y-vt<0 and x﹥0, 180°﹤θ﹤270°; When y-vt=0 and x>0, θ=270°; When y-vt>0 and x>0, 270°<θ<360°; Where (x, y) represents the real-time coordinates of the center point of the welding wire, v represents the welding speed, and the unit parameter is mm / s, and t represents the welding time, and the unit parameter is s.

6. The method for evaluating welding wire feeding stability according to claim 1, characterized in that: Based on the change of the friction resistance, the change of the eccentricity and the change of the azimuth, evaluating the wire feeding stability during welding includes the following steps: The standard deviation of friction resistance is obtained based on the change of friction resistance, the standard deviation of eccentricity is obtained based on the change of eccentricity, and the standard deviation of azimuth is obtained based on the change of azimuth; When the standard deviation of friction resistance σ≤0.5, the standard deviation of eccentricity σ≤0.2, and the standard deviation of azimuth angle σ≤5, the wire feeding stability of the welding wire is judged to be excellent.

7. The method for evaluating welding wire feeding stability according to claim 1, characterized in that: Based on the change of the friction resistance, the change of the eccentricity and the change of the azimuth, evaluating the wire feeding stability during welding includes the following steps: The standard deviation of friction resistance is obtained based on the change of friction resistance, the standard deviation of eccentricity is obtained based on the change of eccentricity, and the standard deviation of azimuth is obtained based on the change of azimuth; The wire feeding stability of the welding wire is judged to be good when at least one of the following conditions is met: Friction resistance standard deviation 0.5<σ≤3; Standard deviation of eccentricity 0.2<σ≤0.5; The standard deviation of the azimuth angle is 5≤σ≤10.

8. The method for evaluating welding wire feeding stability according to claim 1, characterized in that: Based on the change of the friction resistance, the change of the eccentricity and the change of the azimuth, evaluating the wire feeding stability during welding includes the following steps: The standard deviation of friction resistance is obtained based on the change of friction resistance, the standard deviation of eccentricity is obtained based on the change of eccentricity, and the standard deviation of azimuth is obtained based on the change of azimuth; When at least one of the following conditions is met, the wire feeding stability of the welding wire is judged to be poor: Friction resistance standard deviation σ>3; The standard deviation of eccentricity σ>0.5; The azimuth standard deviation σ>10.

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