Control method and device for filler-free welding of stainless steel thin-wall tank

Abstract

The invention discloses a stainless steel thin-wall tank filler-free welding control method and device which are applied to a controller, and the method comprises the steps that geometric data and physical parameters of a stainless steel thin-wall tank to be welded are obtained, and a welding formula database is constructed; in combination with a welding formula database, a welding execution movement track is given, and a welding optimization index is determined; initial welding process parameters are given based on the welding execution movement track and the welding formula database, welding is started to be executed through a welding execution mechanism, and the welding process parameters comprise the first welding process parameter and the second welding process parameter; real-time first welding process parameters are obtained and adjusted; and a real-time second welding process parameter is obtained, and the second welding process parameter is optimized in real time according to the welding constraint model in combination with the target function determined based on the welding optimization index until filler-free welding of the stainless steel thin-wall tank is completed. According to the method, the welding parameters can be accurately controlled, adjusted and optimized, and the welding quality and efficiency of the thin-wall tank are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of welding control, and particularly relates to a control method and device for fillerless welding of stainless steel thin-walled tanks. Background Art

[0002] With the development of industries such as food processing, chemical engineering, and pharmaceuticals, the demand for stainless steel thin-walled tanks is increasing day by day. In the production processes of these industries, stainless steel thin-walled tanks are widely used for storing and transporting various liquids and gases due to their good corrosion resistance, hygiene, and lightweight characteristics. However, the welding technology of stainless steel thin-walled tanks faces many challenges.

[0003] In the prior art, methods such as manual arc welding, gas shielded welding, or laser welding are usually used for welding stainless steel thin-walled tanks, but there are problems such as large welding deformation, wide heat affected zone, and low welding efficiency.

[0004] Patent CN113843504B discloses an automated welding equipment and method for thin-walled non-rotating tank barrels, including a conveying device, a shaping device, a welding device, a control device, an information acquisition device, and a support device. The conveying device includes a linear track and a support device that can move on it. The support device includes a roller rack for supporting the tank barrel during installation and shaping, and a mandrel for supporting the shaping device. The tank barrel to be welded is sleeved outside the shaping device during installation. The welding device includes a plurality of annular rails arranged in the area where the weld is located and a welding head that can move around the annular rails. During the welding process, the control system controls each welding head to move uniformly along its respective annular rail to complete the welding of adjacent tank barrels. This invention only requires a small amount of manual intervention, reduces the labor intensity of workers, reduces the dependence on the experience of welding workers, and the automated operation improves the welding efficiency and quality. However, the welding device used in this solution has a fixed structure and poor adaptability to tank barrels of different sizes. The welding trajectory in the disclosed welding method is single, and the parameters during the welding process cannot be adjusted and optimized in real time. In addition, the welding quality is not quantitatively controlled.

[0005] Therefore, how to customize personalized welding solutions for different thin-walled tank bodies, establish a quantitative relationship between welding quality and welding parameters, and precisely control and adjust the parameters during the welding process are problems that need to be solved urgently by those skilled in the art. Summary of the Invention

[0006] In view of the defects existing in the above-mentioned prior art, the present invention provides a control method and device for filler-free welding of stainless steel thin-walled tanks, which can customize personalized welding schemes for stainless steel thin-walled tanks of different materials and sizes, design welding trajectories adapted to the thin-walled tank body, and accurately control and adjust the parameters during the welding process based on the quantitative relationship between the welding quality and the welding process parameters, thereby improving the welding quality and efficiency of stainless steel thin-walled tanks.

[0007] In a first aspect, the present invention provides a control method for filler-free welding of stainless steel thin-walled tanks, which is applied to a controller and includes the following steps:

[0008] Obtain the geometric data and physical parameters of the to-be-welded stainless steel thin-walled tank, and construct a welding recipe database;

[0009] Combined with the welding recipe database, give the welding execution motion trajectory and determine the welding optimization index;

[0010] Based on the welding execution motion trajectory and the welding recipe database, give the initial welding process parameters and start welding through the welding execution mechanism. Among them, the welding process parameters include the first welding process parameters and the second welding process parameters;

[0011] Obtain the real-time first welding process parameters, and adjust the first welding process parameters in combination with the welding recipe database and the welding execution motion trajectory;

[0012] Obtain the real-time second welding process parameters, combine with the objective function determined based on the welding optimization index, and optimize the second welding process parameters in real time according to the welding constraint model until the filler-free welding of the stainless steel thin-walled tank is completed.

[0013] Furthermore, the geometric data includes the tank diameter, height and wall thickness, and the physical parameters include the material type. Constructing the welding recipe database specifically includes:

[0014] Based on the material type and wall thickness of the to-be-welded stainless steel thin-walled tank, determine the welding fusion temperature range and the central temperature value;

[0015] Based on the welding fusion temperature range and the central temperature value, determine the range of the shielding gas pressure during the welding process and the safety gap with the to-be-welded stainless steel thin-walled tank;

[0016] Collect the geometric data, physical parameters, fusion temperature range, central temperature value, shielding gas pressure range and safety gap, and give the welding recipe database.

[0017] Furthermore, combining with the welding recipe database, giving the welding execution operation trajectory specifically includes the following steps:

[0018] Establish a welding space coordinate system;

[0019] Based on the geometric data of the stainless steel thin-walled tank to be welded, determine the number of spot welds distributed circumferentially along the tank body, the number of welding circles along the height direction of the tank body, and the height interval between adjacent welding circles, and give the coordinates of the spot welds in the welding space coordinate system to generate the spot welding execution motion trajectory;

[0020] Based on the spot welds distributed circumferentially along the tank body, generate the full welding execution motion trajectory;

[0021] Connect the spot welding execution motion trajectory and the full welding execution motion trajectory to form the welding execution motion trajectory.

[0022] Furthermore, the welding optimization indexes include deformation indexes, heat input rate, and shielding gas consumption rate. The deformation indexes include displacement deformation amount, angular deformation amount, and transverse shrinkage amount;

[0023] The first welding process parameters include shielding gas pressure and the position of the laser welding torch;

[0024] The second welding process parameters include laser welding torch power, welding speed, and shielding gas flow rate.

[0025] Furthermore, the welding execution mechanism includes a laser welding torch. Give the initial welding process parameters and start welding through the welding execution mechanism, specifically including:

[0026] Control the laser welding torch to move to the initial position of the welding execution motion trajectory;

[0027] Give the laser welding torch focal length based on the safety clearance, give the initial laser welding torch power based on the central temperature value, and the initial welding speed;

[0028] Set the initial shielding gas flow rate and pressure, turn on the shielding gas, and start welding based on the welding execution motion trajectory;

[0029] Furthermore, obtain the real-time first welding process parameters, and combine the welding recipe database and the welding execution motion trajectory to adjust the first welding process parameters, specifically including:

[0030] The welding control mechanism converts the obtained position of the laser welding torch into coordinate data in the welding space coordinate system and compares and analyzes it with the welding execution motion trajectory;

[0031] Based on the comparison and analysis results, give the control signal of the welding execution mechanism to adjust the position of the laser welding torch in real time;

[0032] The welding control mechanism compares and analyzes the obtained shielding gas pressure with the shielding gas pressure range in the welding recipe database;

[0033] Based on the comparison and analysis results, give the control signal of the pressure regulating valve to adjust the shielding gas pressure in real time.

[0034] Furthermore, determine the objective function based on the welding optimization index, including:

[0035] Determine the coupling relationship between the displacement deformation and the angular deformation, and give the first deformation index and the corresponding first weight coefficient;

[0036] Combine the angular deformation and the wall thickness, and give the second deformation index and the corresponding second weight coefficient;

[0037] Combine the transverse shrinkage and the welding speed, and give the third deformation index and the corresponding third weight coefficient;

[0038] Fuse the first deformation index, the second deformation index and the third deformation index to determine the deformation index;

[0039] Give the first priority coefficient, the second priority coefficient and the third priority coefficient corresponding to the deformation index, the heat input rate and the shielding gas consumption rate respectively, and determine the objective function.

[0040] Furthermore, the deformation index is specifically expressed as:

[0041]

[0042] In the formula, D total is the deformation index, k1, k2, k3 are the first weight coefficients, k D is the deformation coupling factor, D1, D2, D3 are the displacement deformation, the angular deformation and the transverse shrinkage respectively, δ is the wall thickness, v is the welding speed, φ are the displacement deformation index and the first wall thickness index respectively;

[0043] The objective function is specifically expressed as:

[0044] f = w1 * ln(1 + D total ) + w2 * (Q t / Q ref ) S + w3 * (G t / G ref ) T

[0045] In the formula, f is the objective function, w1, w2, w3 are the second weight coefficients, D total is the deformation index, Q t is the heat input rate, Q ref is the reference value of the heat input rate, G t is the shielding gas consumption rate, G ref is the reference value of the shielding gas consumption rate, S, T are the heat input rate index and the shielding gas consumption rate index respectively.

[0046] Further, a welding constraint model is constructed, including:

[0047] Establish the constraint relationship between the second welding process parameters and the displacement deformation amount, and set the boundary constraint conditions for the displacement deformation amount;

[0048] Establish the constraint relationship between the second welding process parameters and the angular deformation amount, and set the boundary constraint conditions for the angular deformation amount;

[0049] Establish the constraint relationship between the second welding process parameters and the transverse shrinkage amount, and set the boundary constraint conditions for the transverse shrinkage amount;

[0050] Establish the constraint relationship between the second welding process parameters and the heat input rate, and establish the constraint relationship between the second welding process parameters and the shielding gas consumption rate;

[0051] Respectively set the boundary constraint conditions for the heat input rate and the shielding gas consumption rate.

[0052] Further, in combination with the objective function determined based on the welding optimization index, according to the welding constraint model, the second welding process parameters are optimized in real time, including the following steps:

[0053] 1) Randomly generate N triples of the second welding process parameters, where the triple of the second welding process parameters includes the laser welding torch power, the welding speed, and the shielding gas consumption rate;

[0054] 2) According to the objective function, obtain the first value corresponding to each triple of the second welding process parameters;

[0055] 3) Randomly select m triples of the second welding process parameters, compare their corresponding first values, and select the triple of the second welding process parameters with the largest first value. Repeat the random selection process until n triples of the second welding process parameters are selected, where m < N and n < N;

[0056] 4) Perform a first operation on the n triples of the second welding process parameters selected with a first probability to generate new triples of the second welding process parameters. Match all the newly generated triples of the second welding process parameters with the welding constraint model, and screen to obtain n' triples of the second welding process parameters, where the first operation refers to randomly selecting k parameter items for exchange between two triples of the second welding process parameters, and k ≤ 3;

[0057] 5) Perform a second operation on the n' triples of the second welding process parameters selected with a second probability to generate new triples of the second welding process parameters. Match all the newly generated triples of the second welding process parameters with the welding constraint model, and screen to obtain n'' triples of the second welding process parameters, where the second operation refers to randomly changing k parameter items in the triple of the second welding process parameters, and k ≤ 3;

[0058] 6) Repeat steps 3), 4), and 5) until the termination condition is reached. In each iteration, obtain and record the maximum value of the first numerical value and the corresponding triple of the second welding process parameters.

[0059] 7) Compare the maximum values of the first numerical value recorded in each iteration, and select the one with the largest maximum value of the first numerical value and the corresponding triple of the second welding process parameters as the optimal second welding process parameters.

[0060] On the second aspect, the present invention also provides a control device for the fillerless welding of stainless steel thin-walled tanks, which adopts any one of the control methods for the fillerless welding of stainless steel thin-walled tanks described above, and includes:

[0061] A welding setting module, which obtains the geometric data and physical parameters of the to-be-welded stainless steel thin-walled tank and constructs a welding recipe database.

[0062] A welding control module, which is used to combine the welding recipe database, give the welding execution motion trajectory, and determine the welding optimization index.

[0063] Based on the welding execution motion trajectory and the welding recipe database, give the initial welding process parameters and start welding through the welding execution mechanism. Among them, the welding process parameters include the first welding process parameters and the second welding process parameters.

[0064] Obtain the real-time first welding process parameters, and combine the welding recipe database and the welding execution motion trajectory to adjust the first welding process parameters.

[0065] Obtain the real-time second welding process parameters, combine the objective function determined based on the welding optimization index, and optimize the second welding process parameters in real time according to the welding constraint model until the fillerless welding of the stainless steel thin-walled tank is completed.

[0066] The control method and device for the fillerless welding of stainless steel thin-walled tanks provided by the present invention have at least the following beneficial effects:

[0067] (1) By constructing a welding recipe database adapted to the geometric data and physical parameters of the stainless steel thin-walled tank, a welding execution motion trajectory adapted to the geometric data of the tank body can be planned, and the corresponding initial welding process parameters can be set, which has good welding adaptability and flexibility.

[0068] (2) Through the real-time monitoring and adjustment of the first welding process parameters, the welding environment is made to meet the welding requirements, and the welding trajectory is accurately controlled without deviation; through the real-time monitoring and optimization of the second welding process parameters, the optimal second welding process parameters are obtained, the heat input is accurately controlled, the welding deformation is minimized, the consumption of the shielding gas is strictly restricted, and energy is saved and the environment is protected.

[0069] (3) The entire welding process requires no manual intervention, achieving welding automation, which can reduce labor intensity, shorten the welding cycle, and improve the welding efficiency of stainless steel thin-walled tanks.

[0070] (4) By optimizing the welding indicators, a quantitative relationship between the welding quality and the second welding process parameters was established, and the second welding process parameters were optimized based on this, improving the welding quality. Description of the Drawings

[0071] Figure 1 It is a flowchart of a control method for fillerless welding of a stainless steel thin-walled tank provided by the present invention;

[0072] Figure 2 It is a schematic diagram of the optimization process of the second welding process parameters in a certain embodiment provided by the present invention;

[0073] Figure 3 It is a schematic diagram of a control device for fillerless welding of a stainless steel thin-walled tank provided by the present invention;

[0074] Figure 4 It is a schematic diagram of the actuator of a control device for fillerless welding of a stainless steel thin-walled tank provided in a certain embodiment of the present invention.

[0075] Description of the reference numerals: 410 - X-axis of the three-axis servo slide, 420 - Y-axis of the three-axis servo slide, 430 - Z-axis of the three-axis servo slide, 440 - R-axis of the three-jaw self-centering servo turntable, 450 - laser welding torch, 460 - origin signal sensor of the three-jaw self-centering servo turntable, 470 - three-jaw self-centering turntable, 480 - stainless steel thin-walled tank to be welded, 490 - spot welding schematic position of the stainless steel thin-walled tank. Detailed Embodiments

[0076] In order to better understand the above technical solutions, the following will describe the above technical solutions in detail in conjunction with the drawings in the specification and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0077] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms of "a", "the" and "said" used in the embodiments of the present invention and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. "Multiple" generally includes at least two.

[0078] It should also be noted that the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a commodity or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or elements inherent to such commodity or device. Without further limitation, an element defined by the statement "comprising one..." does not exclude the presence of additional identical elements in the commodity or device comprising said element.

[0079] The wall thickness of the stainless steel thin-walled tank is usually between 0.5 mm and 5 mm, and in the fields of food, beverage, pharmaceutical, small chemical containers, etc., the wall thickness is more commonly between 0.8 mm and 3 mm.

[0080] During the filler-free welding process of the stainless steel thin-walled tank, problems such as welding slag, spatter, easy burn-through and air leakage through pores are likely to occur. Therefore, a welding control method that can precisely control the welding process is needed to reduce manual intervention in the welding process, improve production efficiency and reduce production costs. The control method needs to be able to precisely control welding parameters such as welding temperature, welding speed and welding position to ensure welding quality. At the same time, the control method also needs to monitor parameters such as temperature, shielding gas pressure and oxygen content during the welding process in real time to ensure the normal progress of the welding control process and the safety of the working environment.

[0081] As Figure 1 shown, in the first aspect, the present invention provides a control method for filler-free welding of a stainless steel thin-walled tank, which is applied to a controller and includes the following steps:

[0082] Obtain the geometric data and physical parameters of the stainless steel thin-walled tank to be welded, and construct a welding recipe database;

[0083] Combined with the welding recipe database, give the welding execution motion trajectory and determine the welding optimization index;

[0084] Based on the welding execution motion trajectory and the welding recipe database, give the initial welding process parameters and start welding through the welding execution mechanism, where the welding process parameters include the first welding process parameters and the second welding process parameters;

[0085] Obtain the real-time first welding process parameters, and combined with the welding recipe database and the welding execution motion trajectory, adjust the first welding process parameters;

[0086] Obtain the real-time second welding process parameters, combine with the objective function determined based on the welding optimization index, and according to the welding constraint model, optimize the second welding process parameters in real time until the filler-free welding of the stainless steel thin-walled tank is completed.

[0087] By constructing a welding recipe database and giving the welding execution motion trajectory, the initial welding process parameters can be accurately set. During the welding process, the adjustment and optimization of the welding process parameters can ensure that the welding process is always in the best state and improve the weld quality.

[0088] In specific implementation, the geometric data includes the tank diameter, height and wall thickness, and the physical parameters include the material type. Constructing the welding recipe database specifically includes:

[0089] Based on the material type and wall thickness of the stainless steel thin-walled tank to be welded, determine the welding fusion temperature range and the center temperature value;

[0090] Based on the welding fusion temperature range and the center temperature value, determine the protective gas pressure range during the welding process and the safety gap from the stainless steel thin-walled tank to be welded;

[0091] Collect geometric data, physical parameters, temperature, pressure and safety gap, and give the welding recipe database.

[0092] Since the thermal conductivity and thermal expansion coefficients of different stainless steel materials (such as 304 stainless steel, 316 stainless steel, 321 stainless steel) are different, and their viscosities and fluidities in the molten state are different, it affects the penetration depth of the molten pool and the weld formation. The stainless steel thin-walled tanks with different wall thicknesses also have different heat conduction and thermal cycle performances. Therefore, different welding fusion temperature ranges are required during welding to ensure good wettability and fluidity and avoid problems such as undercut, lack of fusion or burn-through. By referring to the welding process manual, the welding fusion temperature range of the stainless steel thin-walled tank to be welded can be determined.

[0093] In this example, the calculation method of the center temperature value is:

[0094]

[0095] In the formula, T Z is the center temperature value, T H is the upper limit value of the welding fusion temperature range, and T L is the lower limit value of the welding fusion temperature range.

[0096] By obtaining the geometric data and physical parameters of the stainless steel thin-walled tank, the welding fusion temperature range and the center temperature value during welding can be determined, providing a basis for setting the initial power of the laser welding torch.

[0097] At different welding temperatures, the metal activity of stainless steel is different, resulting in different oxidation / nitriding tendencies, and thus different requirements for the protective gas pressure. Within the welding fusion temperature range, a certain protective gas pressure is also required to maintain the required heat conduction and molten pool shape. The welding temperature also affects the thermal expansion degree at the welding point and the laser beam focusing position. Reasonably setting the safety gap according to the welding fusion temperature range can avoid the collision between the laser welding torch and the welding point and avoid the deviation of the laser focus.

[0098] In this example, by referring to the welding process manual, referring to similar welding cases, referring to welding experimental data, etc., the protection gas pressure range and safety gap under different fusion temperature ranges are determined.

[0099] The obtained geometric data, physical parameters, and determined data such as temperature, pressure, and safety gap are assembled into a welding recipe database, which can provide a geometric data basis for the generation of the welding execution motion trajectory and provide a basis for the setting of welding process parameters.

[0100] In a certain implementation manner, in combination with the welding recipe database, the welding execution operation trajectory is given, which may include the following steps:

[0101] Establish a welding space coordinate system;

[0102] Based on the geometric data of the stainless steel thin-walled tank to be welded, determine the number of spot welding points distributed along the circumferential direction of the tank body, the number of welding circles along the height direction of the tank body, and the height interval between adjacent welding circles, and give the coordinates of the spot welding points in the welding space coordinate system to generate the spot welding execution motion trajectory;

[0103] Based on the spot welding points distributed along the circumferential direction of the tank body, generate the full welding execution motion trajectory;

[0104] Connect the spot welding execution motion trajectory and the full welding execution motion trajectory to form the welding execution motion trajectory.

[0105] In this example, as Figure 4 shown, in combination with the geometric shape of the stainless steel thin-walled tank to be welded and the specific structure of the welding execution mechanism, a welding space coordinate system is established. The center of the bottom of the stainless steel thin-walled tank to be welded is used as the origin to establish a three-dimensional space rectangular coordinate system. The x-axis and y-axis are in the horizontal plane, and the z-axis is perpendicular to the horizontal plane and upward. The welding execution mechanism in this example includes a welding slide table and a welding turntable. The welding slide table is a three-axis servo slide table, and the welding turntable is a three-jaw self-centering servo turntable. The x-axis, y-axis, and z-axis of the welding space coordinate system are respectively parallel to the X-axis, Y-axis, and Z-axis of the three-axis servo slide table. The R-axis is located in a plane perpendicular to the Z-axis and can rotate around the Z-axis. The three-jaw self-centering servo turntable is located on the R-axis. A laser welding gun is fixed on the Y-axis of the three-axis servo slide table. A three-jaw self-centering fixture is provided on the three-jaw self-centering servo turntable for fixing the stainless steel thin-walled tank to be welded. The three-jaw self-centering servo turntable can rotate around its own axis, thereby driving the stainless steel thin-walled tank to be welded to rotate. An origin signal sensor is provided on the circumferential side wall of the three-jaw self-centering servo turntable for measuring the rotation angle of the three-jaw self-centering servo turntable and resetting.

[0106] The space coordinate system can also be established in other ways according to the actual welding situation, subject to the unique determination of the position of the stainless steel thin-walled tank to be welded and the position of the laser welding gun, which is not limited herein.

[0107] Geometric data of the stainless steel thin-walled tank to be welded, including the height H, diameter D, and wall thickness δ of the thin-walled tank. According to the actual welding requirements, determine the spot welding point number n distributed along the circumferential direction of the tank body, the number of welding circles m along the height direction of the tank body, the height interval h between adjacent welding circles, and other spot welding position parameters, and satisfy the relationship: h = H / m. By reasonably determining the spot welding point number n, the number of welding circles m, and the height interval h, the welds can be evenly distributed, ensuring welding quality and structural strength, and reducing welding defects.

[0108] After determining the spot welding position parameters, give the coordinates of the spot welding points in the welding space coordinate system:

[0109] When the spot welding points are evenly distributed along the circumferential direction of the tank body, for the j-th (j = 0, 1, 2,..., n - 1) spot welding point on the i-th (i = 0, 1, 2,..., m - 1) circle, its coordinates are:

[0110]

[0111] z = i·h

[0112] Record the coordinates of all spot welding points as the set P = {(x ij , y ij , z ij )}.

[0113] According to the coordinates of the spot welding points in the welding space coordinate system, generate the spot welding execution motion trajectory, providing a basis for the motion trajectory of the laser welding gun and the rotation angle and speed of the welding turntable.

[0114] In this example, the distribution of the spot welding points can be set evenly along the circumferential direction of the tank body, making the input of welding heat more uniform, balancing the welding stress during welding, and reducing the welding deformation caused by local overheating. It can also be set that the spot welding points are non-uniformly distributed according to factors such as the geometric dimensions of the tank body and the specific welding position requirements.

[0115] When generating the spot welding execution motion trajectory, considering the circumferential distribution of the spot welding points, the coordinates of the spot welding points can be numbered and sorted. First, sort them in ascending order according to the welding circle number i, and then sort the spot welding points within the same welding circle in ascending order according to the number j.

[0116] For the spot welding points within the same welding circle, it can be planned that the laser welding gun welds in sequence according to the spot welding point numbers, avoiding frequent back-and-forth switching of the laser welding gun and reducing the motion path of the laser welding gun. When the spot welding points within the same welding circle are evenly distributed, it can also be planned that the laser welding gun performs symmetric spot welding and determine the rotation angle of the welding turntable each time.

[0117] Between adjacent welding circles, it can be planned that the laser welding gun moves vertically to minimize the moving distance in the vertical direction (the z-axis direction in the welding space coordinate system).

[0118] A full-weld execution movement trajectory is a circular trajectory that sequentially connects all the spot welds within the same welding circle. The circular trajectories on different welding circles form multiple full-weld execution movement trajectories.

[0119] Connecting the spot-weld execution movement trajectory and the full-weld execution movement trajectory gives the final welding execution movement trajectory.

[0120] During the welding process of a thin-walled stainless steel tank, certain indicators are required to control and evaluate the welding quality. This method uses deformation indicators, heat input rate, and shielding gas consumption rate as welding optimization indicators to measure the welding quality. The deformation indicator is further subdivided into displacement deformation amount, angular deformation amount, and transverse contraction amount. The welding process parameters are divided into first welding process parameters and second welding process parameters. The first welding process parameters are used to maintain the welding environment to meet the requirements and ensure that the welding trajectory does not deviate. The second welding process parameters are quantitatively related to the welding optimization indicators. By seeking the optimal second welding process parameters, the welding quality can be accurately controlled.

[0121] In a certain embodiment, the welding optimization indicators include deformation indicators, heat input rate, and shielding gas consumption rate. The deformation indicators include displacement deformation amount, angular deformation amount, and transverse contraction amount.

[0122] Among them, the deformation indicator D total is used to measure the comprehensive deformation degree of the weld seam, including displacement deformation amount D1, angular deformation amount D2, and transverse contraction amount D3. Position sensors can be set at the weld seam monitoring points to monitor their position changes in the welding space coordinate system, and then each deformation indicator can be obtained.

[0123] The displacement deformation amount D1 can be defined as the Euclidean distance between the monitoring points before and after welding, which is used to measure the displacement of the monitoring points and reflects the degree of overall shape deviation of the monitoring points.

[0124] According to the spatial coordinates (x before , y before , z before ) of the monitoring point before welding and the spatial position coordinates (x after , y after , z after ) after welding, the displacement deformation amount can be obtained:

[0125]

[0126] The angular deformation amount D2 can be defined as the angle between the normal directions of the monitoring points before and after welding, which is used to measure the angular deformation degree of the monitoring points.

[0127] According to the normal direction vector n of the monitoring point before welding before =(a before, b before , c before ) and the normal direction vector n after welding after =(a after , b after , c after ), the angular deformation angle can be obtained as follows:

[0128]

[0129] The transverse shrinkage D3 can be defined as the difference in the radial distance between the monitoring point and the axis of the tank before and after welding.

[0130] According to the radial distance R of the monitoring point from the axis of the tank before welding before , and the radial distance R of the monitoring point from the axis of the tank after welding after the transverse shrinkage can be obtained as follows:

[0131] D3 = |R after - F before |.

[0132] The heat input rate Q t is defined as the welding energy input per unit length of the weld, which determines the penetration depth, the width of the heat-affected zone, and the deformation amount. Since the wall thickness of the stainless steel thin-walled tank is very small, overheating is extremely likely to cause deformation or burn-through. Determining the minimum effective heat input is the key to reducing deformation and residual stress, which can make the energy output by the laser welding torch more accurate, ensure the uniformity of the penetration depth and width of the weld, avoid over-burning defects, and improve the weld quality.

[0133] The shielding gas consumption rate G t is defined as the volume of shielding gas consumed per unit length of the weld, which is used to quantify the production cost and is determined by the shielding gas flow rate o and the welding speed v.

[0134] The first welding process parameters include the shielding gas pressure and the position of the laser welding torch; the second welding process parameters include the power of the laser welding torch, the welding speed, and the shielding gas flow rate.

[0135] In a certain embodiment, the welding actuator includes a laser welding torch. Given the initial welding process parameters, the welding is started through the welding actuator, which specifically includes:

[0136] Controlling the laser welding torch to move to the initial position of the welding execution movement trajectory;

[0137] Based on the safety gap, the focal length of the laser welding torch is given, and based on the central temperature value, the initial power of the laser welding torch is given, and the initial welding speed is set;

[0138] Setting the initial shielding gas flow rate and pressure, turning on the shielding gas, and starting the welding based on the welding execution movement trajectory.

[0139] Obtain real-time first welding process parameters, and adjust the first welding process parameters in combination with the welding recipe database and the welding execution motion trajectory, specifically including:

[0140] The welding control mechanism converts the obtained position of the laser welding torch into coordinate data in the welding space coordinate system, and compares and analyzes it with the welding execution motion trajectory;

[0141] Based on the comparison and analysis results, give a control signal to the welding execution mechanism to adjust the position of the laser welding torch in real time;

[0142] The welding control mechanism compares and analyzes the obtained shielding gas pressure with the shielding gas pressure range in the welding recipe database;

[0143] Based on the comparison and analysis results, give a control signal to the pressure regulating valve to adjust the shielding gas pressure in real time.

[0144] In this example, the laser welding torch is controlled by a welding slide, and the stainless steel thin-walled tank to be welded is controlled by a three-jaw self-centering servo turntable. The three-jaw self-centering servo turntable includes a three-jaw self-centering fixture, a centering and pressing mechanism, and a servo-driven rotating mechanism. The welding execution mechanism controls the laser welding torch to perform spot welding first and then full welding according to the welding execution motion trajectory.

[0145] Before spot welding, the position sensor in the sensor module of the centering and pressing mechanism will detect the position of the stainless steel thin-walled tank to be welded placed on the three-jaw self-centering fixture. When the position state meets the conditions, the tank body is centered and clamped and the workpiece to be welded is pressed. Specifically, the three-jaw self-centering fixture positions the stainless steel thin-walled tank to be welded according to the center line of the tank body, and accurately docks with the workpiece to be welded controlled by the centering and pressing mechanism to ensure that the fusion edges are aligned without dislocation. The servo-driven rotating mechanism is used to control the stainless steel thin-walled tank to be welded and the workpiece to be welded to rotate around the axis of the welding turntable or rotate around the Z axis of the three-axis servo slide table. After the pressing monitoring sensor in the sensor module obtains the signal that the workpiece to be welded is pressed in place, it transmits the detected position state to the welding control mechanism, and the welding control mechanism issues a spot welding execution instruction according to the position state.

[0146] During spot welding operation, the Y axis of the three-axis servo slide controls the laser welding torch to move to the initial position of the spot welding execution motion trajectory, align with the initial spot welding point, and adjust the distance between the laser welding torch and the thin-walled tank to the safety gap. Set the focal length of the laser welding torch based on the safety gap to ensure that the energy focus point of the laser welding torch always accurately aligns with the welding point to be welded. Give the initial power of the laser welding torch based on the center temperature value to ensure that the welding temperature can reach the center temperature value and make the spot welding point fuse. And set the laser scanning speed, pulse width, pulse frequency and output duty cycle of the laser welding torch.

[0147] Set the initial shielding gas pressure and flow, turn on the shielding gas, turn on the laser welding gun, execute the motion trajectory based on the spot welding, coordinate the welding slide and the welding turntable, and control the laser welding gun to perform welding at each spot welding point.

[0148] Preferably, when an even number of spot welds are evenly distributed along the circumference of the tank body, a symmetrical spot welding method is used. Fix the position of the laser welding gun and complete the welding of the first spot weld first; turn off the laser welding gun, and the servo-driven rotation mechanism controls the stainless steel thin-walled tank to be welded to rotate 180°; turn on the laser welding gun and weld the symmetrical points; turn off the laser welding gun, and the servo-driven rotation mechanism controls the stainless steel thin-walled tank to be welded to rotate a certain angle (the angle between adjacent spot welds in the same welding circle); turn on the laser welding gun and weld the adjacent spot welds; turn off the laser welding gun, and the servo-driven rotation mechanism controls the stainless steel thin-walled tank to be welded to rotate 180°; turn on the laser welding gun and weld the adjacent symmetrical points; repeat the above steps until all spot welds in the same welding circle are welded.

[0149] Specifically, for all spot welding points P in the same welding circle (i-th circle) ij ,y ij ,z ij )}(j=0,1,2,…,n-1), first complete the initial point (x i0 ,y i0 ,z i0 ) and then complete the symmetrical points in sequence The adjacent points of the symmetrical point The symmetrical point of the adjacent point (x i1 ,y i1 ,z i1 ) until all spot welds within the same welding circle (i-th circle) are completed. The laser welding gun can be controlled to be fixed, and the servo-driven rotation mechanism can control the stainless steel thin-walled tank to be welded to rotate the corresponding angle to complete the symmetrical spot welding operation in sequence; the laser welding gun can also be controlled to move to achieve symmetrical spot welding operation.

[0150] Due to the thin wall thickness of stainless steel thin-walled tanks, thermal stress can cause deformation if the welding sequence is asymmetrical. In this example, a symmetrical spot welding sequence is used. By gradually fixing the welding positions, the rigidity of the tank is enhanced and weld quality is prevented from being affected by workpiece shifting or shaking during subsequent welding. Symmetrical spot welding also balances heat input and heat distribution during welding, reducing residual deformation caused by localized thermal stress. Uniform heating also prevents weld defects such as cracks or incomplete penetration caused by stress concentration.

[0151] After spot welding is completed, the laser welding gun is turned off, and the welding slide and welding turntable are adjusted to the starting position and angle of the full welding execution motion trajectory respectively.

[0152] After the spot welding operation, solder joints are formed at the key positions of the welds of the stainless steel thin-walled tank, initially connecting the components to be welded. However, since the wall thickness of the stainless steel thin-walled tank is usually only 1-3 mm, spot welding is difficult to ensure long-term sealing, especially for corrosive media or vacuum conditions. Therefore, full welding operation is also required. By continuously welding to fill the weld gap, the sealing performance of the weld is ensured, meeting the storage requirements of the thin-walled tank for liquids or gases. It also further improves the stress distribution of the tank body, enhances the bearing capacity and compressive strength of the tank body, and extends the service life.

[0153] Before full welding, control the laser welding torch to move to the initial position of the full welding execution motion trajectory, set the focal length of the laser welding torch, the initial power of the laser welding torch, set the initial welding speed, and set the initial flow rate and pressure of the shielding gas.

[0154] Turn on the shielding gas and start welding based on the full welding execution motion trajectory.

[0155] During the welding process, the acquisition and monitoring mechanism monitors the first welding process parameters in real time and transmits the first welding process parameters to the welding control mechanism in real time. Among them, the first welding process parameters include the position of the laser welding torch and the pressure of the shielding gas.

[0156] Specifically, set a position encoder to monitor the position of the laser welding torch and provide real-time feedback on the position of each control axis (the X-axis, Y-axis, Z-axis of the welding slide and the R-axis of the welding turntable), achieving high-precision positioning of the laser welding torch in the welding space coordinate system. Ensure that when welding stainless steel thin-walled tanks of different specifications and sizes, the laser welding torch can achieve precise positioning of 0.01 mm, and can accurately and continuously weld the 1-2 mm weld seam. At the same time, ensure the laser beam focusing accuracy to accurately control the temperature at the welding point, avoid heat diffusion, and reduce energy loss; set a pressure transmitter to monitor the pressure of the shielding gas, and a pressure sensor can also be set to monitor whether the fixture is loose.

[0157] The welding control mechanism receives the first welding process parameters, and combines the welding recipe database and the welding execution motion trajectory to adjust the first welding process parameters in real time.

[0158] Specifically, after the welding control mechanism converts the position of the laser welding torch fed back by the position encoder into coordinate data in the welding space coordinate system, the algorithm fitting module in the welding control mechanism compares and analyzes this coordinate data with the full-weld execution motion trajectory. Based on the comparison and analysis results, a correction and adjustment signal is generated, which is sequentially transmitted to the welding execution mechanism through the I / O digital quantity output module and the bus communication interface to control the welding slide table to drive the laser welding torch to adjust its position, so that the laser welding torch performs welding according to the full-weld execution motion trajectory. Through comparison and analysis, the deviation between the actual position of the laser welding torch and the full-weld execution motion trajectory can be discovered in real time, and a correction and adjustment signal can be generated in a timely manner to accurately control the welding slide table and the turntable, ensuring that the laser welding torch always strictly performs welding according to the full-weld execution motion trajectory, realizing precise tracking and control of the welding trajectory, improving the welding accuracy, making the weld formation more beautiful, flat and smooth, without undercut, and the welding pattern uniform, fine and of consistent width.

[0159] The welding control mechanism also compares and analyzes the received shielding gas pressure with the shielding gas pressure range in the welding recipe database, and generates an adjustment signal based on the comparison and analysis results, which is transmitted to the pressure regulating valve in the welding execution mechanism through the analog quantity output interface and the bus communication interface to adjust the pressure of the shielding gas. By precisely adjusting the pressure of the shielding gas, the shielding effect during welding is ensured, preventing the weld from oxidation or gas absorption, and improving the surface quality and mechanical properties of the weld.

[0160] In this example, the shielding gas is provided by the gas blowing execution mechanism. The gas blowing execution mechanism uses argon as the shielding gas, and the shielding gas pressure range is 0.4 - 0.6 Mpa. The welding control mechanism controls the gas blowing execution mechanism to blow out the inert gas to isolate and protect the welding area, so as to reduce the generation of defects such as weld oxidation, nitridation, blackening and deformation. The gas blowing execution mechanism includes an analog quantity gas pressure regulating valve, a pressure transmitter, an electromagnetic control cut-off valve, and a welding torch gas blowing nozzle. The analog quantity gas pressure regulating valve is used to adjust the pressure of the inert gas; the pressure transmitter is used to detect the pressure of the inert gas in real time; the electromagnetic control cut-off valve is used to control the on and off of the inert gas during welding to reduce the waste of the inert gas; the welding torch gas blowing nozzle is used to blow gas for isolation during welding to protect the molten pool and prevent the flying welding slag from entering the welding torch and damaging the focusing lens inside the welding torch. The inert gas blown out by the gas blowing execution mechanism can isolate the air, prevent the active gases such as oxygen and nitrogen from contacting the stainless steel molten pool, avoid the oxidation of the weld to generate harmful oxides, and prevent the chromium in the stainless steel from oxidizing and losing its corrosion resistance. At the same time, the low-temperature inert gas plays a cooling role, which can reduce the thermal stress and thermal deformation of the weld during welding, and also prevent the weld from changing color due to high-temperature oxidation, ensuring the appearance of the product.

[0161] During the welding process, the acquisition and monitoring mechanism monitors in real time and transmits the second welding process parameters to the welding control mechanism. Specifically, a speed sensor is set to monitor the welding speed, a flow sensor is set to monitor the flow rate of the shielding gas, a power meter is set to monitor the power of the laser welding torch, and a temperature sensor can also be set to monitor the welding temperature.

[0162] In a certain embodiment, the welding control mechanism combines the objective function determined based on the welding optimization index and, according to the welding constraint model, optimizes the second welding process parameters in real time.

[0163] As can be seen from the foregoing, the welding optimization index includes the deformation index D total , the heat input rate Q t , and the shielding gas consumption rate G t . The deformation index includes the displacement deformation amount D1, the angular deformation amount D2, and the transverse shrinkage amount D3. The second welding process parameters include the power P of the laser welding torch, the welding speed v, and the shielding gas flow rate o.

[0164] Determine the coupling relationship between the displacement deformation amount and the angular deformation amount, and give the first deformation index and the corresponding first weight coefficient; combine the angular deformation amount and the wall thickness, and give the second deformation index and the corresponding second weight coefficient; combine the transverse shrinkage amount and the welding speed, and give the third deformation index and the corresponding third weight coefficient; fuse the first deformation index, the second deformation index, and the third deformation index to determine the deformation index, which can be specifically expressed as:

[0165]

[0166] In the formula, D total is the deformation index, represents the first deformation index, D2*δ -φ represents the second deformation index, ln(1 + D3 / v) represents the third deformation index. k1, k2, and k3 are the first weight coefficient, the second weight coefficient, and the third weight coefficient respectively, and k D is the deformation coupling factor, D1, D2, and D3 are the displacement deformation amount, the angular deformation amount, and the transverse shrinkage amount respectively. δ is the wall thickness, and v is the welding speed. φ are the displacement deformation exponent and the first wall thickness exponent respectively, which can be determined according to the actual welding situation. The first weight coefficient, the second weight coefficient, and the third weight coefficient can be empirical values or obtained through experiments. The deformation coupling factor can be obtained through experiments, and a typical value is 0.8. The first deformation index, the second deformation index, and the third deformation index can also take other forms according to the actual welding situation.

[0167] Since the displacement deformation amount D1 is not linear, when the displacement deformation increases, its influence on the overall deformation shows a non-linear growth (for example, when the displacement exceeds a certain threshold, it may cause the structure to become unstable). The displacement deformation exponent This non - linear relationship can be adjusted, and the value can be taken between 1 and 2 according to the actual welding situation, and a higher weight is given when the displacement deformation is large.

[0168] During the welding process, the displacement deformation amount D1 and the angular deformation amount D2 will affect each other and there is a coupling relationship. A larger displacement deformation amount will cause the structure to be asymmetric, which will further exacerbate the angular deformation. Therefore, the product term D1*D2 in this example is used to characterize this coupling effect, and k D can reflect the coupling strength between D1 and D2. The first deformation index can also take other forms according to the actual welding situation.

[0169] Thin - walled structures are more prone to angular deformation under welding heat input. The negative exponential term δ of the wall thickness -φ is used to represent the sensitivity of the angular deformation amount to the wall thickness. The value of φ can be obtained from empirical formulas or numerical simulations. In this example, it takes values from 0.5 to 0.8. The second deformation index can also take other forms according to the actual welding situation.

[0170] The transverse shrinkage amount D3 is closely related to the welding speed. When the welding speed is high, the heat input rate decreases, and the transverse shrinkage amount usually decreases. The ratio of D3 to v is used to eliminate the influence brought by the speed change and reflect the strength of the transverse shrinkage itself. The logarithmic form ln(1 + D3 / v) in this example is used to indicate that when the transverse shrinkage amount exceeds a certain value, the influence trend on the deformation index becomes slower. The third deformation index can also take other forms according to the actual welding situation.

[0171] After determining the deformation index, by giving the first - priority coefficient, the second - priority coefficient and the third - priority coefficient corresponding to the deformation index, the heat input rate and the shielding gas consumption rate respectively, the objective function can be determined. The objective function can be specifically expressed as:

[0172] f = w1*ln(1 + D total ) + w2*(Q t / Q ref ) S + w3*(G t / G ref ) T (2)

[0173] In the formula, f is the objective function, w1, w2, and w3 are the first - priority coefficient, the second - priority coefficient, and the third - priority coefficient respectively, D total is the deformation index, Q t is the heat input rate, Q ref is the reference value of the heat input rate, G t is the shielding gas consumption rate, G refis the reference value of the shielding gas consumption rate. The first priority coefficient, the second priority coefficient, and the third priority coefficient can be empirical values or obtained through experiments. The reference value of the heat input rate and the reference value of the shielding gas consumption rate can both be obtained through experiments. S and T are the heat input rate exponent and the shielding gas consumption rate exponent respectively, and both can be obtained through experiments. In this example, S takes values from 1.8 to 2.5, and T takes values from 2.7 to 3.3.

[0174] The objective function in this example comprehensively considers the engineering constraints and economic cost requirements during the welding of the stainless steel thin-walled tank. The deformation term ln(1 + D total ) is used to characterize the influence of the deformation index on the objective function. When D total is small, it increases approximately linearly. When D total is large, the growth slows down, reflecting that a small deformation of the thin-walled tank is allowed during the welding process, but the leakage caused by larger deformations needs to be suppressed. The heat input rate term (Q t / Q ref ) S is used to reflect the non-linear influence of the heat input rate on the objective function, indicating that when the heat input rate exceeds a certain threshold during the actual welding process, the grain coarsening rate increases sharply. The shielding gas consumption rate term (G t / G ref ) T is used to characterize that the welding cost increases super-linearly with the shielding gas consumption. G ref is the reference value of the shielding gas consumption rate. When the shielding gas consumption rate exceeds the reference value, turbulence will occur, and there is a risk of shielding failure.

[0175] Based on the relationships between the welding optimization indicators and the second welding process parameters, as well as the constraint boundaries of each welding optimization indicator itself, a welding constraint model is constructed.

[0176] The heat input rate Q t is determined by the laser welding torch power P and the welding speed v:

[0177] Q t = P / v (3)

[0178] The heat input rate Q t also needs to satisfy the boundary constraint conditions:

[0179] Q min ≤Q t ≤Q max (4)

[0180] In the formula, Q min , Q max are the minimum boundary value and the maximum boundary value of the heat input rate, which are determined by the actual welding equipment and welding requirements.

[0181] The shielding gas consumption rate G tDetermined by the shielding gas flow rate o and the welding speed v, and satisfies:

[0182] G t =(λ1K t +λ2K P )o / v, and λ1 + λ2 = 1 (5)

[0183] In the formula, λ1 and λ2 are the fourth weight coefficient and the fifth weight coefficient respectively. K t is the temperature correction coefficient, and K P is the pressure correction coefficient, which are determined by the actual welding temperature and the shielding gas pressure respectively. The fourth weight coefficient and the fifth weight coefficient can be empirical values or obtained through experiments. In this example, K t takes values from 1.02 to 1.15, and K P takes values from 1.05 to 1.20.

[0184] The shielding gas consumption rate G t also needs to satisfy the boundary constraint conditions:

[0185] G min ≤G t ≤G max (6)

[0186] In the formula, G min and G max are the minimum boundary value and the maximum boundary value of the shielding gas consumption rate, which are determined by the actual welding equipment and the welding requirements.

[0187] The displacement deformation amount D1 is affected by the laser welding torch power P, the welding speed v, and the shielding gas flow rate o, and satisfies the relationship:

[0188] D1 = l1*P ξ / (v ζ )*e -α*o (7)

[0189] In the formula, l1 is the displacement deformation coefficient, which can be determined by fitting experimental data. ξ is the first power exponent, which can be obtained through experiments. In this example, it takes values from 1.1 to 1.5. ζ is the first speed exponent, which can be obtained through experiments. In this example, it takes values from 0.6 to 0.9. α is the gas cooling attenuation coefficient, which can be obtained through experiments. In this example, it takes values from 0.05 to 0.08.

[0190] In addition, the displacement deformation amount D1 needs to not exceed 0.1% of the single-loop weld length L c :

[0191] D1 ≤ 0.001L c (8)

[0192] In the formula, the single-loop weld length L cIt can be uniquely determined after the welding trajectory is generated.

[0193] The angular deformation amount D2 is determined by the laser welding torch power P, the welding speed v, and the shielding gas flow rate o, and satisfies the relationship:

[0194]

[0195] In the formula, l2 is the angular deformation coefficient, which can be determined by fitting experimental data. is the first flow rate exponent, which can be obtained through experiments. In this example, it takes values from 0.1 to 0.5. θ is the second wall thickness exponent, which can be obtained through experiments. In this example, it takes values from 0.5 to 1.

[0196] In addition, the edge offset caused by the angular deformation amount D2 should not exceed half of the wall thickness δ, that is:

[0197] D2 ≤ arctan(0.5 * δ / H) (10)

[0198] In the formula, H is the height of the tank body, which is obtained from the welding recipe database.

[0199] The transverse shrinkage amount D3 is determined by the laser welding torch power P and the welding speed v, and satisfies:

[0200]

[0201] In the formula, l3 is the transverse shrinkage coefficient, which can be determined by fitting experimental data. is the second power exponent, which can be determined through experiments. In this example, it takes values from 0.7 to 1. τ is the second speed exponent, which can be obtained through experiments. In this example, it takes values from 0.6 to 0.9.

[0202] In addition, the transverse shrinkage amount D3 needs to satisfy the boundary constraint and not exceed 0.05% of the single - loop weld length L c That is:

[0203] D3 ≤ 0.0005L c (12)

[0204] In the formula, the single - loop weld length L c It can be uniquely determined after the welding trajectory is generated.

[0205] In addition, the laser welding torch power P also needs to satisfy its own constraints:

[0206] P min ≤ P ≤ P max (13)

[0207] In the formula, P min is the laser welding torch power corresponding to the lower limit value of the fusion temperature range, and P max is the laser welding torch power corresponding to the upper limit value of the fusion temperature range.

[0208] The welding constraint model is established by equations (3) to (13).

[0209] It can be understood that the values of various deformation indexes, heat input rate values, shielding gas consumption rate values, parameter values in the welding recipe database, various welding process parameter values, etc. in this example are all normalized, and the values of each variable are dimensionless to ensure the universality and numerical stability of the model. The values of each weight coefficient, each priority coefficient, each exponential value, coupling factor value, etc. in this example are all dimensionless.

[0210] Based on the objective function and the welding constraint model, the welding control mechanism adopts a welding optimization algorithm to optimize the laser welding torch power P, welding speed v, and shielding gas flow o in real time, and obtains the optimal second welding process parameters. As Figure 2 shown, the specific process is as follows:

[0211] 1) According to the process limitations of the actual welding equipment, within the constraints of each second welding process parameter, N (determined by the processing capacity of the welding control mechanism, and can be selected according to the actual welding situation) groups of second welding process parameter triples are randomly generated by floating-point coding or other random methods, denoted as (P, v, o).

[0212] 2) For each second welding process parameter triple, according to the objective function, obtain the corresponding first value:

[0213]

[0214] In the formula, F represents the first value, f is the value of the objective function, and ∈ is a very small positive number (such as ∈ = 10 -6 ). The first value is a value obtained by converting the value of the objective function, and is used to map the value of the objective function to a new value range. The larger the first value, the smaller the corresponding objective function value, indicating that this group of second welding process parameters is better. Other forms of the first value expression can also be adopted according to the actual welding requirements.

[0215] 3) Randomly select m (m < N) second welding process parameter triples, compare their corresponding first values, and select the second welding process parameter triple with the largest corresponding first value. Repeat the random selection process until n (n < N) second welding process parameter triples are selected.

[0216] 4) Set the first probability P1 (e.g., P1 = 0.7), and perform a first operation on the n groups of second welding process parameter triples selected in step 3) with the first probability to generate new second welding process parameter triples. For all newly generated second welding process parameter triples, check whether they meet the constraint conditions in the welding constraint model. If they do not meet, discard them; if they meet, retain them to obtain n' second welding process parameter triples. Here, the first operation refers to randomly selecting 1 - 3 parameters between two groups of second welding process parameters for exchange. For example, for two groups of second welding process parameters (P1, v1, o1) and (P2, v2, o2), the random number generator generates a random number between 0 and 1. If this random number is less than the first probability (0.7), then exchange some parameter items of the two groups of second welding process parameters. For example, exchange the second parameter item v to obtain new second welding process parameter triples: (P1, v2, o1), (P2, v1, o2).

[0217] 5) Set the second probability P2 (e.g., P2 = 0.1), and perform a second operation on the n' second welding process parameter triples obtained in step 4) with the second probability to generate new second welding process parameter triples. For all newly generated second welding process parameter triples, check whether they meet the constraint conditions in the welding constraint model. If they do not meet, discard them; if they meet, retain them to obtain n” second welding process parameter triples. Here, the second operation refers to randomly adjusting the parameter values in a certain second welding process parameter triple. For example, for a certain second welding process parameter triple (P3, v3, o3), the random number generator generates a random number between 0 and 1. If this random number is less than the second probability (0.1), then randomly adjust some parameter items of this second welding process parameter triple to new values within their own constraint ranges. For example, randomly adjust the first parameter item P to obtain a new second welding process parameter triple: (P3′, v3, o3).

[0218] 6) Repeat steps 3), 4), and 5) until the set number of iterations (e.g., 100 times) is reached or the first value converges. In each iteration, obtain and record the maximum value of the first value and the corresponding second welding process parameter triple.

[0219] 7) Compare the maximum values of the first value recorded in each iteration, select the one with the largest maximum value of the first value, find the corresponding second welding process parameter triple, and output it as the optimal second welding process parameter.

[0220] After the welding control mechanism obtains the optimal second welding process parameter, it outputs a control signal to control the welding actuator to perform welding operations with the laser gun power, welding speed, and shielding gas flow rate in the optimal second welding process parameter.

[0221] The welding control mechanism, assuming the second welding process parameters meet the constraints, comprehensively considers welding optimization indicators to accurately determine the optimal combination of laser welding gun power, welding speed, and shielding gas flow. This precise control of heat input reduces weld distortion and saves energy. Precise control of shielding gas consumption reduces production costs and meets environmental requirements while ensuring cooling and protective atmosphere requirements.

[0222] In one embodiment, the control method for welding a stainless steel thin-walled tank without filler further includes:

[0223] Set up a display module for real-time display of welding process parameters, fault diagnosis information, alarm information, etc.

[0224] Automatically monitor and record relevant parameters and data such as laser welding gun power curve, welding temperature curve, welding gun motion actuator servo torque curve, welding speed, etc., to facilitate optimization analysis after welding is completed, provide a reference basis for the next welding, and achieve better welding results.

[0225] like Figure 3 As shown, in a second aspect, the present invention further provides a control device for welding a stainless steel thin-walled tank without filler, which adopts any of the above-mentioned control methods for welding a stainless steel thin-walled tank without filler, specifically comprising:

[0226] The welding setting module obtains the geometric data and physical parameters of the stainless steel thin-walled tank to be welded and builds a welding formula database;

[0227] The welding control module is used to combine the welding recipe database to provide the welding execution motion trajectory and determine the welding optimization index;

[0228] Based on the welding execution motion trajectory and the welding recipe database, initial welding process parameters are given, and welding is started by a welding execution mechanism, wherein the welding process parameters include a first welding process parameter and a second welding process parameter;

[0229] Acquire real-time first welding process parameters, and adjust the first welding process parameters in combination with a welding recipe database and a welding execution motion trajectory;

[0230] The real-time second welding process parameters are obtained, combined with the objective function determined based on the welding optimization index, and according to the welding constraint model, the second welding process parameters are optimized in real time until the filler-free welding of the stainless steel thin-walled tank is completed.

[0231] Although the preferred embodiments of the present invention have been described, additional changes and modifications can be made to these embodiments by those skilled in the art once they learn the basic creative concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications falling within the scope of the present invention. Obviously, those skilled in the art can make various changes and variations to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A control method for welding of stainless steel thin-walled tanks without filler, applied to a controller, characterized in that: The following steps are involved: Obtain the geometric data and physical parameters of the stainless steel thin-walled tank to be welded and build a welding formula database; Combined with the welding recipe database, the welding execution motion trajectory is given and the welding optimization index is determined; Based on the welding execution motion trajectory and the welding recipe database, initial welding process parameters are given, and welding is started by a welding execution mechanism, wherein the welding process parameters include a first welding process parameter and a second welding process parameter; Acquire real-time first welding process parameters, and adjust the first welding process parameters in combination with a welding recipe database and a welding execution motion trajectory; The real-time second welding process parameters are obtained, combined with the objective function determined based on the welding optimization index, and according to the welding constraint model, the second welding process parameters are optimized in real time until the filler-free welding of the stainless steel thin-walled tank is completed.

2. The control method for filler-free welding of stainless steel thin-walled tanks according to claim 1 is characterized in that: Geometric data includes tank diameter, height, and wall thickness, while physical parameters include material type. A welding recipe database is constructed, specifically including: Determine the welding fusion temperature range and center temperature value based on the material type and wall thickness of the stainless steel thin-walled tank to be welded; Based on the welding fusion temperature range and center temperature value, determine the shielding gas pressure range during welding and the safe gap with the stainless steel thin-walled tank to be welded; The geometric data, physical parameters, fusion temperature range, center temperature value, shielding gas pressure range and safety gap are collected to provide a welding recipe database.

3. The control method for filler-free welding of stainless steel thin-walled tanks according to claim 2, characterized in that: Combined with the welding recipe database, the welding execution trajectory is given, which specifically includes the following steps: Establish welding space coordinate system; Based on the geometric data of the stainless steel thin-walled tank to be welded, the number of spot welds distributed along the circumference of the tank, the number of weld circles along the height direction of the tank, and the height interval between adjacent weld circles are determined. The coordinates of the spot weld points in the welding space coordinate system are given, and the spot welding execution motion trajectory is generated. Based on the spot welding points distributed along the circumference of the tank, a full welding execution motion trajectory is generated; The spot welding execution motion trajectory and the full welding execution motion trajectory are connected to form a welding execution motion trajectory.

4. The control method for filler-free welding of stainless steel thin-walled tanks according to claim 3 is characterized in that: Welding optimization indicators include deformation index, heat input rate and shielding gas consumption rate. Deformation index includes displacement deformation, angular deformation and lateral shrinkage. The first welding process parameters include shielding gas pressure and laser welding gun position; The second welding process parameters include laser welding gun power, welding speed, and shielding gas flow rate.

5. The control method for filler-free welding of stainless steel thin-walled tanks according to claim 4 is characterized in that: The welding actuator includes a laser welding gun, which gives the initial welding process parameters and starts welding through the welding actuator, specifically including: Control the laser welding gun to move to the initial position of the welding execution motion trajectory; The focal length of the laser welding gun is given based on the safety gap, the initial laser welding gun power is given based on the center temperature value, and the initial welding speed is set; Set the initial shielding gas flow and pressure, turn on the shielding gas, and start welding based on the welding execution motion trajectory; Acquire real-time first welding process parameters, and adjust the first welding process parameters in combination with the welding recipe database and the welding execution motion trajectory, specifically including: The welding control mechanism converts the acquired laser welding gun position into coordinate data in the welding space coordinate system, and compares and analyzes it with the welding execution motion trajectory; Based on the comparison and analysis results, the control signal of the welding actuator is given to adjust the position of the laser welding gun in real time; The welding control unit compares and analyzes the obtained shielding gas pressure with the shielding gas pressure range in the welding formula database; Based on the comparison and analysis results, a control signal for the pressure regulating valve is given to adjust the shielding gas pressure in real time.

6. The control method for filler-free welding of stainless steel thin-walled tanks according to claim 5, characterized in that: Determine the objective function based on the welding optimization indicators, including: Determine the coupling relationship between the displacement deformation and the angular deformation, and provide a first deformation index and a corresponding first weight coefficient; Combining the angular deformation and the wall thickness, a second deformation index and a corresponding second weight coefficient are given; Combining the transverse shrinkage and welding speed, the third deformation index and the corresponding third weight coefficient are given; fusing the first deformation index, the second deformation index, and the third deformation index to determine a deformation index; The first priority coefficient, the second priority coefficient and the third priority coefficient corresponding to the deformation index, the heat input rate and the shielding gas consumption rate are given respectively, and the objective function is determined.

7. The control method for filler-free welding of stainless steel thin-walled tanks according to claim 6, characterized in that: The deformation index is specifically expressed as: Where D total is the deformation index, k1, k2, k3 are the first weight coefficient, the second weight coefficient, and the third weight coefficient respectively, k D is the deformation coupling factor, D1, D2, and D3 are the displacement deformation, angular deformation, and lateral shrinkage, respectively; δ is the wall thickness; v is the welding speed. φ are the displacement deformation index and the first wall thickness index respectively; The objective function is specifically expressed as: f=w1*ln(1+D total )+w2*(Q t / Q ref ) S +w3*(G t / G ref ) T Where f is the objective function, w1, w2, and w3 are the first priority coefficient, the second priority coefficient, and the third priority coefficient, respectively. total is the deformation index, Q t is the heat input rate, Q ref is the reference value of heat input rate, G t is the shielding gas consumption rate, G ref is the reference value of shielding gas consumption rate, S and T are heat input rate index and shielding gas consumption rate index respectively.

8. The control method for filler-free welding of stainless steel thin-walled tanks according to claim 6 or 7, characterized in that: Construct welding constraint models, including: Establishing a constraint relationship between the second welding process parameters and the displacement deformation, and setting a boundary constraint condition for the displacement deformation; Establishing a constraint relationship between the second welding process parameters and the angular deformation, and setting a boundary constraint condition for the angular deformation; Establishing a constraint relationship between the second welding process parameters and the transverse shrinkage, and setting a boundary constraint condition for the transverse shrinkage; Establishing a constraint relationship between the second welding process parameter and the heat input rate, and establishing a constraint relationship between the second welding process parameter and the shielding gas consumption rate; Set the boundary constraints of heat input rate and shielding gas consumption rate respectively.

9. The control method for filler-free welding of stainless steel thin-walled tanks according to claim 8, characterized in that: In combination with the objective function determined based on the welding optimization index and according to the welding constraint model, the second welding process parameters are optimized in real time, including the following steps: 1) randomly generating N second welding process parameter triplets, wherein the second welding process parameter triplets include laser welding gun power, welding speed, and shielding gas consumption rate; 2) obtaining a first value corresponding to each second welding process parameter triplet according to the objective function; 3) randomly selecting m second welding process parameter triplets, comparing their corresponding first values, selecting the second welding process parameter triplet with the largest first value, and repeating the random selection process until n second welding process parameter triplets are selected, where m < N, n < N; 4) Performing a first operation on the selected n second welding process parameter triplets with the first probability to generate new second welding process parameter triplets, matching all newly generated second welding process parameter triplets with the welding constraint model, and screening n ' a second welding process parameter triplet, wherein the first operation refers to randomly selecting k parameter items between the two second welding process parameter triplet for exchange, k≤3; 5) Use the second probability to select n ' Perform the second operation on the second welding process parameter triples to generate new second welding process parameter triples, match all newly generated second welding process parameter triples with the welding constraint model, and screen out n ” a second welding process parameter triplet, wherein the second operation refers to randomly changing k parameter items in the second welding process parameter triplet, k≤3; 6) Repeat steps 3), 4), and 5) until the termination condition is reached. In each iteration, obtain and record the maximum value of the first value and the corresponding second welding process parameter triplet; 7) Compare the maximum values of the first values recorded in each iteration, and select the second welding process parameter triple with the largest maximum value of the first value and the corresponding triple as the optimal second welding process parameter.

10. A control device for welding stainless steel thin-walled tanks without filler, characterized in that: The control method for welding a stainless steel thin-walled tank without filler according to any one of claims 1 to 9 comprises: The welding setting module obtains the geometric data and physical parameters of the stainless steel thin-walled tank to be welded and builds a welding formula database; The welding control module is used to combine the welding recipe database to provide the welding execution motion trajectory and determine the welding optimization index; Based on the welding execution motion trajectory and the welding recipe database, initial welding process parameters are given, and welding is started by a welding execution mechanism, wherein the welding process parameters include a first welding process parameter and a second welding process parameter; Acquire real-time first welding process parameters, and adjust the first welding process parameters in combination with a welding recipe database and a welding execution motion trajectory; The real-time second welding process parameters are obtained, combined with the objective function determined based on the welding optimization index, and according to the welding constraint model, the second welding process parameters are optimized in real time until the filler-free welding of the stainless steel thin-walled tank is completed.

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