Automatic welding control method

Abstract

Provided is an automatic welding control method for adjusting the movement of an automatic welding device, the automatic welding device comprising a rotating mechanism, a welding torch angle adjusting mechanism and a lifting motion mechanism, for welding a weld between a branch pipe and a main pipe, the branch pipe being arranged non-parallel to the main pipe, the method comprising the following steps: collecting an existing weld image using an image vision system, extracting a weld edge contour, and drawing a weld characteristic curve; constructing a curved surface trajectory function and a welding torch angle adjusting function according to the weld characteristic curve, the curved surface trajectory function comprising a rotating motion function and a lifting motion function; and causing the welding torch angle adjusting mechanism, the rotating mechanism and the lifting motion mechanism to move according to the angle adjusting function, the rotating motion function and the lifting motion function respectively. The method can enable the automatic welding device to realize continuous and stable welding.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of welding, in particular to the field of welding control method. BACKGROUND

[0002] Welding is a key technology for nuclear power plant construction, however, a large number of engineering welding in the process of nuclear power construction is still mainly operated by hand, especially for some complex weld seam trajectories involved in the stable pressure vessel, reactor pressure vessel, steam generator, condenser, cooling tower and adapter pipeline, because the weld seam angles of different spatial positions are different, the welding parameters change in the welding process, and the welding difficulty is increased.

[0003] Automatic welding needs to realize good identification and posture planning of the trajectory, and the current method for solving the welding trajectory planning welding is to rely on teaching reproduction, record identification process, and finally reproduction in the welding process. The common welding automation method adjusts the trajectory in the following ways, such as through 3D point cloud model, using D-H to establish kinematics formula, establishing mathematical model to solve the welding gun motion trajectory, laser beam and the like. Among them, the point cloud model is to convert the three-dimensional point cloud coordinate system to the coordinate system of the welding robot, and the welding robot moves according to the coordinate points on the coordinate system; the D-H method for establishing kinematics formula is to obtain the posture and coordinate position of the welding robot end in the base coordinate system of the welding robot, so as to realize the motion trajectory; the mathematical model is to solve the discrete point coordinate position on the three-dimensional complex welding trajectory, so that the motion mechanism moves according to the discrete points to realize the control of the welding trajectory; the laser beam method refers to taking the welding trajectory data obtained as the output of the laser welder to plan the welding trajectory.

[0004] The above methods all realize the motion trajectory by displacement according to multiple coordinate positions, which is not continuous and accurate enough, resulting in that the trajectory curve is often not smooth and continuous, and is easy to impact the mechanical structure. In addition, the above method also needs to use multiple interpolation methods to improve the stability of the motion, which is relatively complex. SUMMARY

[0005] An object of the present application is to provide an automatic welding control method, which can realize continuous and stable welding of the automatic welding equipment.

[0006] The automatic welding control method for adjusting the movement of the automatic welding equipment includes a rotating mechanism, a welding gun angle adjusting mechanism and a lifting motion mechanism, and is used for welding the weld seam between the branch pipe and the main pipe. The branch pipe is arranged non-parallel to the main pipe. The method comprises the following steps:

[0007] An image vision system is used to collect the existing weld seam image, extract the weld seam edge contour, and draw the weld seam feature curve;

[0008] Based on the weld seam characteristic curve, a surface trajectory function and a welding torch angle adjustment function are constructed. The surface trajectory function includes a rotational motion function and a lifting motion function.

[0009] The welding torch angle adjustment mechanism, the rotary mechanism, and the lifting motion mechanism are respectively moved according to the angle adjustment function, the rotary motion function, and the lifting motion function.

[0010] In one or more embodiments, a first intersection point between the main pipe column surface and the weld feature curve is obtained, a second intersection point between the branch pipe column surface and the weld feature curve is obtained, and a lifting motion function and a welding torch angle adjustment function are constructed based on the first and second intersection points.

[0011] In one or more embodiments, the independent variables of the surface trajectory function include time and the angular velocity of the rotary mechanism, and the dependent variables include the rotation angle of the rotary mechanism and the motion speed of the lifting mechanism.

[0012] In one or more embodiments, the input current of the rotary mechanism is constructed as a function of the angular velocity of the rotary mechanism.

[0013] In one or more embodiments, the input current of the lifting motion mechanism is constructed as a function of the motion speed of the lifting motion mechanism.

[0014] In one or more embodiments, the angular velocity of the rotary mechanism is adjusted to obtain the optimal rotary angle and the movement speed of the lifting mechanism.

[0015] In one or more embodiments, the independent variables of the welding torch angle adjustment function include time and the angular velocity of the change in the angle between the branch pipe and the main pipe, and the dependent variable includes the angle of the welding torch relative to the branch pipe or the main pipe.

[0016] In one or more embodiments, the input current of the welding torch angle adjustment mechanism is a function of the angular velocity of the change in the angle between the branch pipe and the main pipe.

[0017] In one or more embodiments, the angle between the branch pipe and the main pipe is obtained using the cosine of the angle between the cylindrical normal vector of the branch pipe and the cylindrical normal vector of the main pipe.

[0018] In one or more embodiments, the first intersection point and the second intersection point are used to construct... Where r is the branch pipe radius and R is the main pipe radius. θ is the angle between the first intersection point and the direction of ascent and descent, and θ0 is the angle between the second intersection point and the axial direction of the main pipe.

[0019] In one or more embodiments, the cosine value of the included angle is ;use Substituting the cosine value of the included angle, we obtain ; the method for obtaining the included angle between the branch pipe and the main pipe , wherein r is the branch pipe radius, R is the main pipe radius, θ4 is the included angle between the branch pipe and the main pipe, and θ0 is the included angle between the second intersection point and the axial direction of the main pipe.

[0020] In one or more embodiments, the rotary motion function is a proportional function, and the lifting motion function and the angle adjustment function are wave chord functions.

[0021] In one or more embodiments, the curved surface trajectory equation is ,

[0022] , wherein the lifting motion function is , the rotary motion function is , θ0 is the included angle between the welding seam and the intersection point of the branch pipe relative to the axial direction of the main pipe, t0 is the time of the rotary mechanism moving around the branch pipe, ω0 is the angular velocity of the rotary mechanism, R is the main pipe radius, and r is the branch pipe radius.

[0023] In one or more embodiments, the angle adjustment function is , wherein A is the angle adjustment proportional coefficient, C is the angle adjustment constant, t0 is the time of the rotary mechanism moving around the branch pipe, is the angular velocity of the change of the included angle between the branch pipe and the main pipe.

[0024] The above method realizes welding seam trajectory recognition and feature extraction through an image processing algorithm, and based on the welding seam trajectory data, uses a speed waveform control to adjust the lifting trajectory and the welding torch angle. Instead of sequentially displacing, the lifting motion function is used as a one-dimensional speed waveform function, the rotary motion function is used as a two-dimensional trajectory speed waveform function, three-dimensional welding trajectory is realized through the superposition of one-dimensional and two-dimensional, and the welding torch angle adjustment function is constructed to control the overall motion waveform curve of the automatic welding equipment to be smooth, continuous and without inflection points, so that the welding torch motion is continuous and uninterrupted, and is avoided to be impacted by rigidity and flexibility. BRIEF DESCRIPTION OF DRAWINGS

[0025] The above and other features, properties, and advantages of the present application will become more apparent by describing in the following description, taken in conjunction with the accompanying drawings and embodiments, in which:

[0026] Figure 1 is a schematic diagram of the image visual system collecting the welding seam trajectory;

[0027] Figure 2 is a schematic diagram of the welding structure of the main pipe and the branch pipe;

[0028] Figure 3 is a schematic diagram of the included angle between the main pipe and the branch pipe;

[0029] Figure 4A is a schematic diagram of the welding seam imaging plane;

[0030] Figure 4B is a schematic diagram of the extraction of the weld seam edge profile;

[0031] Figure 5 is a schematic diagram of a welding device;

[0032] Figure 6 is a schematic diagram of a female pipe cross section;

[0033] Figure 7 is a schematic diagram of a branch pipe cross section;

[0034] Figure 8 is and schematic diagram of the equality relationship;

[0035] Figure 9 is the angular velocity of the rotary mechanism Z-axis movement speed function waveform graph changing over time;

[0036] Figure 10 is the angular velocity of the rotary mechanism Z-axis movement displacement function waveform graph changing over time;

[0037] Figure 11 is the angular velocity of the rotary mechanism welding gun angle adjustment function waveform graph changing over time;

[0038] Figure 12 is the angular velocity of the rotary mechanism female pipe and branch pipe included angle change function waveform graph changing over time;

[0039] Figure 13 is the angular velocity of the rotary mechanism angular velocity change function of the female pipe and branch pipe included angle waveform graph changing over time;

[0040] Figure 14 is the angular velocity of the rotary mechanism angular velocity change function of the female pipe and branch pipe included angle waveform graph changing over time;

[0041] Figure 15 is the angular velocity of the rotary mechanism angular velocity change function of the female pipe and branch pipe included angle waveform graph changing over time;

[0042] Figure 16 is the input current of the Z-axis motion mechanism under different torque-to-voltage ratios a waveform curve graph changing over time;

[0043] Figure 17 is the input current of the angle adjustment mechanism under different torque-to-voltage ratios a waveform curve graph changing over time. DETAILED DESCRIPTION

[0044] The present application will be further described with reference to the specific examples and drawings, and more details are set forth in the following description in order to fully understand the present application, but the present application can be implemented in many different ways other than the description, and those skilled in the art can make similar generalizations and deductions according to the actual application without departing from the spirit of the present application, so the protection scope of the present application should not be limited by the specific examples.

[0045] It should be noted that these and other subsequent drawings are only examples, and are not drawn to scale, and should not be used as a limitation on the actual claimed protection scope of the present application.

[0046] The present disclosure proposes a welding angle control method based on welding trajectory recognition, which divides a three-dimensional complex trajectory into a one-dimensional motion trajectory in the height direction of the rising and falling edges and a two-dimensional motion trajectory along the circumferential surface, obtains a three-dimensional welding trajectory according to the linkage of the one-dimensional motion trajectory and the two-dimensional motion trajectory, and further realizes continuous movement and angle adjustment of the welding gun.

[0047] The method is suitable for Figure 2 The welding process of the main pipe 100 and the branch pipe 200 is shown, the branch pipe 200 is welded on the main pipe 100 to form a weld 300, and the branch pipe 200 is arranged non-parallel to the main pipe 100.

[0048] Figures 4A-4B Further show the picture and the processed image of the weld. According to the attached Figure 1 , the attached Figure 4A It can be seen that since the welding hole 5 formed by the main pipe 100 and the branch pipe 200 is a bevel, the relative angle θ4 between the main pipe 100 and the branch pipe 200 has different values along one circle of the weld. The intersection of the branch pipe 200 and the main pipe 100 forms the highest point P of the weld and the lowest point Q of the weld, the relative angle θ4 between the main pipe 100 and the branch pipe 200 at the highest point P of the weld is 90°, and the relative angle θ4 between the main pipe 100 and the branch pipe 200 at the lowest point Q of the weld is an acute angle, for example, 60°. The size of the relative angle θ4 between the main pipe 100 and the branch pipe 200 at the lowest point Q of the weld depends on the pipe diameter size of each of the main pipe 100 and the branch pipe 200.

[0049] In the following figures, the X-axis represents the axial direction of the main pipe 100, and the Z-axis represents the lifting direction, i.e., the height direction. Figure 2 In the embodiment shown, the axial direction of the branch pipe 200 is also shown, with the Y-axis orthogonal to the X-axis and Z-axis.

[0050] This method is used to adjust the movement of automatic welding equipment, thereby welding the weld between the branch pipe and the main pipe. Figure 5 A simplified diagram of an automatic welding equipment is shown. The automatic welding equipment includes a rotary mechanism a, a welding torch angle adjustment mechanism b, and a lifting mechanism c. The rotary mechanism a drives the welding torch to rotate around the Z-axis. The welding torch angle adjustment mechanism b is used to adjust the angle between the welding torch and the main pipe or branch pipe. The lifting mechanism c is used to adjust the height of the welding torch relative to the main pipe or branch pipe.

[0051] In some embodiments, a left-right lateral movement mechanism d is also included for adjusting the distance between the welding torch and the branch pipe along the X-axis direction to prevent the welding torch from hitting the branch pipe.

[0052] The method includes the following steps: First, an image vision system 60 is used to acquire weld images of existing welded specimens, accurately segment the bevel area, extract edge contours, and draw weld feature curves; based on the weld feature curves, a surface trajectory function and a lifting motion function are constructed; the welding torch angle adjustment mechanism b, the rotation mechanism a, and the lifting motion mechanism c are made to move according to the angle adjustment function, the rotation motion function, and the lifting motion function, respectively.

[0053] As shown in Figure 4, the weld feature curve 400 is not a planar curve, but a spatial curve with three-dimensional coordinates of X, Y, and Z.

[0054] Obtain the intersection points of the cylindrical surfaces of branch pipe 200 and main pipe 100 with the weld seam. Figure 6 This diagram shows the first intersection point A formed by the cylindrical surface of the main pipe 100 and the weld characteristic curve 400 on the main pipe section (YOZ plane). Figure 7 This diagram shows the first intersection point B formed by the cylindrical surface of branch pipe 200 and the weld characteristic curve 400 in the branch pipe cross-section (XOY plane). Wherein, Let A be the angle between the first intersection point A and the Z-axis. Let be the angle between the second intersection point B and the X-axis. Branch pipe 200 has a radius r, and main pipe 100 has a radius R.

[0055] The equation of the normal to the branch pipe column surface is: Equation of the normal to the main cylinder .definition The coordinates of the intersection point of the normal line L1 of the main pipe surface and the weld seam are also the coordinates of the first intersection point. is the coordinate of the intersection point of the normal line of the branch pipe cylinder L2 and the weld, that is, the coordinate of the second intersection point. The intersection point coordinates satisfy the following relationships respectively:

[0056] , .

[0057] Further, it can be understood that, for Figures 6-7 the projection curve as shown in FIG. 4, the two included angles and the diameter satisfy the following relationship: Figure 8 , is the branch pipe y-axis displacement of the welding torch, is the main pipe y-axis displacement of the welding torch.

[0058] Back to FIG. 4, in order to obtain the branch pipe and main pipe included angle θ4, the cosine value of the included angle between the branch pipe cylinder normal vector and the main pipe cylinder normal vector is obtained. As the main pipe cylinder normal vector is , the branch pipe cylinder normal vector is , and the cosine value of the included angle between the two normal vectors is .

[0059] According to the branch pipe cylinder normal line equation , the main pipe cylinder normal line equation , and is substituted into the equation:

[0060]

[0061] and according to the above relationship , the following can be obtained: Further, the method for obtaining the included angle between the branch pipe and the main pipe is .

[0062] According to the above geometric relationship, the data of the first intersection point and the second intersection point, the surface trajectory function and the welding torch angle adjustment function are constructed.

[0063] I. Provide a surface trajectory function

[0064] The surface trajectory function includes two parts of the rotation motion function and the lifting motion function. Since the weld connecting the main pipe and the branch pipe is equivalent to a circular motion and a vertical motion, the combination of the circular motion and the lifting motion is required to realize such a trajectory, and therefore the rotation motion function of the surface trajectory function is used for the circular motion, and the lifting motion function is used for the lifting motion.

[0065] The independent variables of the surface trajectory function include time t and the rotation mechanism angular velocity , and the dependent variables include the rotation angle of the rotation mechanism and the motion speed function of the lifting motion mechanism : ​

[0066] The equation of the curved trajectory is , is the time of the rotating mechanism rotating around the support pipe, is the displacement function of the z-axis movement. Within , the rotating mechanism rotates around the support pipe.

[0067] The equation of the curved trajectory includes a proportional function and a wave function. The proportional function can realize the circular movement of 0-360° according to the change of time, and the wave function can make the lifting mechanism realize the change of speed according to the preset function according to the change of time.

[0068] It can be understood that the first part of the equation of the curved trajectory, that is, the rotation angle of the rotating mechanism around the center axis of the support pipe can be represented by the angle of the intersection point of the weld and the support pipe relative to the X-axis , that is , is the speed wave of the two-dimensional trajectory (circular).

[0069] The other part of the equation of the curved trajectory, that is, the z-axis movement speed function of the lifting mechanism, is first obtained from the z-axis movement displacement function . According to the attached Figure 8 , , combined with , the is obtained. The z-axis movement displacement function is differentiated to obtain , which is a one-dimensional trajectory (axis) speed wave curve.

[0070] Therefore, the equation of the curved trajectory is . The curved trajectory equation does not pass through the displacement in sequence, but realizes the three-dimensional welding trajectory by controlling the welding mechanism according to the speed wave of one-dimensional and two-dimensional trajectories. The wave curve is smooth and continuous without inflection point, and the movement is continuous and uninterrupted, so that there is no rigid and flexible impact in the welding process.

[0071] II. Provide a welding gun angle adjusting function

[0072] The welding gun angle adjusting function is a wave function. According to the change of time, the welding gun angle adjusting mechanism can realize the change of the angle of the welding gun according to the preset function.

[0073] The welding gun angle adjusting function is defined as , wherein is the welding gun angle adjusting function, and f( ) is the change function of the angle between the support pipe and the parent pipe. The welding gun is located between the support pipe and the parent pipe during welding. If the welding gun is placed in the middle of the support pipe and the parent pipe, the welding gun angle is: , if it is 1 degree upward or downward in the middle, the welding gun angle is 0.5 ±1°. A is the angle adjustment coefficient, C is the angle adjustment constant, and t1 is any time. Since it is impossible to perfectly match the function curve in actual welding, A and C are adjusted, and the welding angle is manually set according to the requirements and welding conditions in the actual welding process. is the differential of the angle with respect to time, that is, the angular velocity function of the change in the included angle between the branch pipe and the main pipe.

[0074] Since , the included angle between the branch pipe and the main pipe is a function of time , the differential of the included angle between the branch pipe and the main pipe with respect to time :

[0075] .

[0076] Based on this, the angle adjustment function is obtained, where the angular velocity of the change in the included angle between the branch pipe and the main pipe is a kind of wave function. The welding torch angle adjustment mechanism moves according to the angle adjustment function, and the angle of the welding torch is adjusted during the welding process.

[0077] The angle adjustment function is obtained by establishing a mathematical model and solving the relationship between the change in the welding torch angle and the two-dimensional trajectory movement speed according to the geometric relationship. The change in the welding torch angle is directly controlled by controlling the wave form, and the change in the angle is continuous without inflection points, which is relatively smooth.

[0078] III. Obtain the current function of the welding torch angle adjustment mechanism, the rotation mechanism, and the lifting movement mechanism

[0079] The welding torch angle adjustment mechanism, the rotation mechanism, and the lifting movement mechanism can move according to the preset current function.

[0080] For the rotation mechanism, the current function enables the rotation mechanism to change the angular velocity according to the preset current function, which is expressed as , which is a wave function, where is the input current of the rotation mechanism; is a function of the angular velocity .

[0081] Further, , where is the voltage, is the torque, is the linear speed of the rotation mechanism.

[0082] For the lifting movement mechanism, the current function enables the lifting movement mechanism to change the lifting according to the preset current function. The z-axis movement mechanism can change the speed according to the preset current function, which is expressed as wherein is the input current of the z-axis motion mechanism, is a function of . According to , it is arranged that , is the torque, is the speed of the lifting motion mechanism.

[0083] For the welding torch angle adjustment mechanism, the current and the welding torch adjustment angle speed relationship equation , according to , it is arranged that .

[0084] Through the above input current function, the method not only can realize the welding track and the welding torch angle adjustment through the speed control, but also can realize the control through the current. Specifically, by giving the current control function for different objects of controlling the welding torch movement, the speed function is controlled through the current function, and the movement of the specific curved surface track required by the weld and the specific welding torch angle can be realized.

[0085] When R is 10 mm, r is 5 mm, and the angular velocity of the rotary mechanism is 6, 12, and 72 respectively, the z-axis speed waveform curve of the lifting motion mechanism is as shown in Figure 9 , the z-axis displacement waveform curve of the lifting motion mechanism is as shown in Figure 10 , the welding torch angle waveform curve is as shown in Figure 11 , the branch pipe and the parent pipe included angle change waveform curve is as shown in Figure 12 , and the welding torch angular velocity waveform curve is as shown in the attached Figures 13-15 .

[0086] When is 1, 5, and 10 respectively, the current waveform curve, the current waveform curve is as shown in the attached Figure 16 , the attached Figure 17 .

[0087] When , A=3, C=π, changes, the values of other parameters are as shown in Table 1:

[0088] Table 1 Values of each parameter change with time

[0089]

[0090] The above method has the following advantages:

[0091] ​​(1) Through the image processing algorithm to realize the weld seam trajectory recognition and feature extraction, and based on the weld seam trajectory data, using the speed waveform control to adjust the lifting trajectory and the welding torch angle, not through the displacement in turn but according to the lifting movement function as a one-dimensional speed waveform function, the rotation movement function as a two-dimensional trajectory speed waveform function, through the linkage of one-dimensional and two-dimensional to realize three-dimensional welding, and through the construction of the welding torch angle adjustment function, control the overall movement waveform curve of the automatic welding equipment to be smooth, continuous and without inflection point, so that the welding torch movement is continuous and uninterrupted, and the rigid and flexible impact is avoided.

[0092] (2) By giving the current control function for different objects of the welding torch movement, through the current function control speed function, the movement of the specific curved surface trajectory required by the weld seam and the specific welding torch angle can be realized.

[0093] (3) The method establishes the relationship between the trajectory equation, the welding torch angle adjustment and the angular velocity, time, as long as the angular velocity or time is controlled, that is, as long as one parameter is controlled, the complex welding trajectory and the welding torch angle adjustment can be realized at the same time.

[0094] The present application uses specific words to describe the embodiments of the present application. As "one embodiment", "an embodiment", and / or "some embodiments" means a certain feature, structure or characteristic related to at least one embodiment of the present application. Therefore, it should be emphasized and noted that the "an embodiment" or "one embodiment" or "an alternative embodiment" mentioned in different places in the specification does not necessarily refer to the same embodiment. In addition, some features, structures or characteristics in one or more embodiments of the present application can be properly combined.

[0095] Although the present application is disclosed with the preferred embodiments as above, it is not intended to limit the present application, and any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present application. Therefore, any modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application, which does not deviate from the technical solution of the present application, falls within the protection scope defined by the claims of the present application.

Claims

1. An automatic welding control method for adjusting the movement of an automatic welding apparatus including a rotation mechanism, a welding gun angle adjusting mechanism, and a lift motion mechanism for welding a weld between a branch pipe and a main pipe, the branch pipe being disposed non-parallel to the main pipe, characterized by, The method comprises the following steps: An image vision system is used to collect existing weld images, extract weld edge contours, and draw weld characteristic curves; A curved surface trajectory function and a welding torch angle adjustment function are constructed according to the weld characteristic curves, the curved surface trajectory function comprising a rotary motion function and a lifting motion function; The welding torch angle adjustment mechanism, the rotary mechanism, and the lifting motion mechanism are respectively moved according to the angle adjustment function, the rotary motion function, and the lifting motion function; The independent variables of the curved surface trajectory function comprise time and rotary mechanism angular velocity, and the dependent variables comprise the rotary angle of the rotary mechanism and the movement speed of the lifting motion mechanism; The independent variables of the welding torch angle adjustment function comprise time and the change angular velocity of the included angle between the branch pipe and the main pipe, and the dependent variable comprises the angle of the welding torch relative to the branch pipe or the main pipe; The rotary motion function is a proportional function, and the lifting motion function and the angle adjustment function are wave chord functions; The welding gun angle adjustment function θ1 is Wherein A is an angle adjustment proportion coefficient, C is an angle adjustment constant, t0 is the time of the rotating mechanism moving around the branch pipe, t1 is any time, Is the change angular velocity of the branch pipe and the parent pipe included angle, the change angular velocity of the branch pipe and the parent pipe included angle is obtained by differentiating the branch pipe and the parent pipe included angle with respect to time, , θ4 is the branch pipe and the parent pipe included angle; The curved trajectory function is wherein the lifting motion function is , the rotary motion function is , is the included angle of the weld joint and the intersection point of the branch pipe relative to the axial direction of the main pipe, is the time of the rotary mechanism moving around the branch pipe, is the angular velocity of the rotary mechanism, wherein z x is the z-axis motion displacement function, R is the radius of the main pipe, and r is the radius of the branch pipe; Wherein, the Z-axis represents the axial direction of the branch pipe.

2. The automatic welding control method of claim 1, wherein A first intersection point of the main pipe cylindrical surface and the weld characteristic curve is obtained, a second intersection point of the branch pipe cylindrical surface and the weld characteristic curve is obtained, and a lifting motion function and a welding torch angle adjustment function are constructed according to the first intersection point and the second intersection point.

3. The automatic welding control method of claim 1, wherein An input current of the rotary mechanism and the rotary mechanism angular velocity function are constructed.

4. The automatic welding control method of claim 1, wherein, An input current of the lifting motion mechanism and the lifting motion mechanism movement speed function are constructed.

5. The automatic weld control method of claim 1, wherein, The rotary mechanism angular velocity is adjusted to obtain the optimal rotary angle and the movement speed of the lifting motion mechanism.

6. The automatic weld control method of claim 1, wherein, An input current of the welding torch angle adjustment mechanism and the change angular velocity of the included angle between the branch pipe and the main pipe function are constructed.

7. The automatic welding control method of claim 2, wherein, The included angle between the branch pipe and the main pipe is obtained using the included angle cosine value of the cylindrical normal vector of the branch pipe and the cylindrical normal vector of the main pipe.

8. The automatic welding control method of claim 7, wherein, using the first intersection point and the second intersection point, a first line is constructed wherein is an angle between the first intersection point and the lifting direction, is an angle between the second intersection point and the main pipe axial direction.

9. The automatic welding control method of claim 8, wherein, The cosine of the included angle value is ; Using Substituting the cosine of the included angle value, we obtain ; Obtaining the way of calculating the angle between the branch pipe and the parent pipe .

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