A method for optimizing welding process parameters suitable for ultra-high strength steel

Abstract

The present invention discloses a method for optimizing welding process parameters suitable for ultra-high strength steel, which relates to the technical field of continuous annealing welding and includes: initializing the optimization step size of welding parameters, the initial value of the objective function, the number of parameter adjustments, and the parameter adjustment coefficient; calculating the total heat required to form a weld nugget when welding ultra-high strength steel and the effective heat during welding of ultra-high strength steel; calculating the weld thickness after welding ultra-high strength steel; calculating the welding current, welding speed, and electrode pressure; establishing a comprehensive optimization objective function with the highest utilization rate of the total welding heat and the proximity of the calculated weld thickness to the set value of the weld thickness as the goal, solving the minimum value of the comprehensive optimization objective function, and obtaining the optimal welding current, welding speed, and electrode pressure. The present invention ensures the stable operation of the welding machine, improves the actual production efficiency and quality, and brings long-term economic benefits to the unit.

Description

Technical Field

[0001] The present invention relates to the technical field of continuous annealing welding, and particularly to a method for optimizing welding process parameters suitable for ultra-high strength steel. Background Art

[0002] The quality of welding directly affects the surface quality of the finished strip steel. In order to ensure the welding quality and weld thickness at the weld of the front and rear coils of strip steel, welding process parameters need to be set properly. The relevant parameters affecting welding quality are mainly the pressure of the rolling wheel, electrode pressure, welding speed, welding current, and overlap amount. Through on-site investigation, it can be seen that for strip steel within a certain thickness range, the values of the overlap amount and the pressure of the rolling wheel do not change much. The main factors causing the quality of strip welding are welding current, electrode pressure, and welding speed. Among them, the welding current is the direct source of heat required for fusion at the welding point. Too low current will result in insufficient heat generation, causing the strip steel at the welding point to fail to bond. Too large current will cause excessive heat generation, resulting in over-melting or reducing the strength of the weld. Changes in electrode pressure and welding speed will change the welding current and thus affect the welding quality. The electrode pressure affects the distribution of current lines by changing the contact area between the strip steel and the electrode, causing changes in welding resistance and welding current, thereby indirectly affecting the welding quality. The slower the welding speed, the longer the welding time required, and the greater the effective heat generated. This situation will make the weld thinner and cause the weld to crack. On the contrary, insufficient heat generation will result in incomplete penetration, deteriorating the welding quality. Therefore, it is necessary to optimize the parameters affecting welding quality to improve the surface quality and production efficiency of the strip.

[0003] Currently, the research directions at home and abroad are mainly focused on the causes of defects at the weld and preventive measures, the research on factors affecting welding quality, and the analysis of the reasons for weld breakage of the strip. There is no relevant content on optimizing the relevant parameters affecting welding quality to improve the welding quality of the strip. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a method for optimizing welding process parameters suitable for ultra-high strength steel. Considering the influence of welding process parameters on welding quality and weld thickness, a welding process parameter optimization model is established. Through this model, the electrode pressure, welding speed, and welding current are optimized to improve the production efficiency and surface quality of the strip steel.

[0005] In order to achieve the above invention purpose, the present invention adopts the following technical solutions:

[0006] The present invention provides a method for optimizing welding process parameters suitable for ultra-high strength steel, including the following steps executed by a computer:

[0007] Calculate the welding current I, welding speed V, and electrode pressure P;

[0008] Taking the highest utilization rate of the total welding heat and the proximity of the calculated weld thickness to the set value of the weld thickness as the goal, a comprehensive optimization objective function is established: G(X) = ωφ1(X) + (1 - ω)φ2(X);

[0009] where ω is the weighting coefficient of the welding parameter optimization objective function; X = {I, V, P}; φ1(X) and φ2(X) are process functions, F(X) j is the influence function of the welding parameters, is the influence ratio of the welding heat and the weld thickness on the influence function, Q1 is the effective heat during welding, Q is the total heat during welding, H is the weld thickness, H set is the set value of the weld thickness, j is the number of parameter optimization times; is the average value of the influence function, n is the total number of parameters collected before and after welding a coil of strip; I is the current during strip welding, I min ≤ I ≤ I max , V is the welding speed, V min ≤ V ≤ V max , P is the electrode pressure, P min ≤ P ≤ P max ; I min is the minimum current during strip welding, I max is the maximum current during strip welding, V min is the minimum welding speed, V max is the maximum welding speed, P min is the minimum electrode pressure, P max is the maximum electrode pressure;

[0010] Solve the minimum value of the comprehensive optimization objective function to obtain the optimal welding current, welding speed, and electrode pressure.

[0011] Furthermore, solving the minimum value of the comprehensive optimization objective function to obtain the optimal welding current, welding speed, and electrode pressure includes:

[0012] Judge whether G(X) > G cs (X) holds, G cs (X) is the initially set value of the objective function;

[0013] If G(X) > G cs (X) does not hold, then let the parameter adjustment coefficient G cs (X) = G(X), α i = α i+1. Update the values of the welding current, welding speed, or electrode pressure respectively according to the current optimization step size, welding speed optimization step size, and electrode pressure optimization step size, and perform the G(X) iterative calculation and the judgment of whether G(X)>G cs (X) holds;

[0014] If G(X)>G cs (X) holds, judge whether the number of optimized parameters i<3 holds;

[0015] If the number of optimized parameters i<3 holds, then let i = i + 1, and return to the step of calculating the welding parameters I, V, P to optimize the next variable; when i = 1, optimize the welding current I, when i = 2, optimize the welding speed V, and when i = 3, optimize the electrode pressure P;

[0016] If the number of optimized parameters i<3 does not hold, then assign the optimal values of the parameters for this parameter optimization, that is, I zyj = I, V zyj = V, P zyj = P, I zyj is the optimal value of the welding current, V zyj is the optimal value of the welding speed, P zyj is the optimal value of the electrode pressure.

[0017] Furthermore, return to the step of calculating the welding parameters I, V, P to optimize the next variable, including:

[0018] When optimizing I, V and P remain unchanged at the initial values. When the objective function G(X) is the smallest, the value of I at this time is the optimal value;

[0019] When optimizing V, I remains unchanged at the optimal value, and P is the initial value. When the objective function G(X) is the smallest, the value of V at this time is the optimal value;

[0020] When optimizing P, I and V remain unchanged at the optimal values. When the objective function G(X) is the smallest, the value of P at this time is the optimal value.

[0021] Furthermore, it also includes:

[0022] Judge whether j<n holds. If j<n holds, then let j = j + 1 and enter the next parameter optimization process. If j<n does not hold, then output the currently optimized optimal welding process parameters I zyj 、V zyj 、P zyj .

[0023] Furthermore, calculate the total heat required to form a weld nugget during welding, including:

[0024] Calculate the total heat Q required to form the fusion nucleus according to the formula Q = λcA·(ξ s h s + ξ x h x )(b d + b b )ρBΔT;

[0025] Among them, λ is the fusion nucleus melting coefficient, c is the specific heat capacity of the strip, A is the penetration rate, h s is the thickness of the forward strip, h x is the thickness of the rear strip, ξ s is the influence coefficient of the electrode pressure on the thickness of the forward strip steel, ξ x is the influence coefficient of the electrode pressure on the thickness of the rear strip steel, b d is the strip overlap, b b is the strip compensation amount, B is the width of the welded strip, ρ is the strip density, and ΔT is the temperature difference between the normal temperature of the strip steel and the fusion nucleus state.

[0026] Furthermore, calculate the effective heat of strip welding, including:

[0027] According to the formula Calculate the effective heat Q1 of strip welding;

[0028] Among them, t is the welding time of the strip steel by the welding machine, γ is the effective heat calculation coefficient when the welding machine welds ultra-high strength steel, Ce1 is the welding carbon equivalent of the forward strip steel, Ce2 is the carbon equivalent of the rear strip steel, R is the total resistance when welding ultra-high strength steel, α is the influence coefficient of the strip thickness on the effective heat, and β is the influence coefficient of the carbon equivalent on the effective heat.

[0029] Furthermore, calculate the total resistance R when welding ultra-high strength steel, including:

[0030] According to the formula

[0031] Calculate the total resistance R when welding ultra-high strength steel;

[0032] Among them, m is the strip contact coefficient, K c is the coefficient related to the contact material, surface condition, and contact form, ρ0 is the resistivity value of the strip steel at 0°, ρ0 = 9.78×10 -8 Ωm, α1 is the influence coefficient of temperature on resistivity, T is the temperature during strip welding, E2 is the elastic modulus of the strip steel, v2 is the Poisson's ratio, b hls is the thickness of the upper welding wheel, b hlx is the thickness of the lower welding wheel, R hls is the radius of the upper welding wheel, R hlx is the radius of the lower welding wheel, E1 is the elastic modulus of the welding wheel, and v1 is the Poisson's ratio.

[0033] Further, calculating the weld thickness of the strip includes:

[0034] Calculating the weld thickness H of the strip according to the formula ;

[0035] where P N is the pressure of the rolling wheel, B p is the influence coefficient of the electrode pressure on the weld thickness, B Q is the influence coefficient of the heat on the weld thickness, b d is the overlap amount of the strip, b b is the compensation amount of the strip, B L is the influence coefficient of the overlap amount on the weld thickness.

[0036] Advantages and positive effects of the present invention: By studying the influence of welding current, welding speed, and electrode pressure on the weld quality, the present invention establishes a comprehensive optimization model for welding process parameters. Through the optimization of these parameters, the stability of the welder operation is ensured, the actual production efficiency and quality are improved, and long-term economic benefits are brought to the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0038] Figure 1 is a comprehensive optimization flow chart of welding process parameters suitable for ultra-high strength steel according to the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] In order to enable those skilled in the art to better understand the solutions of the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0040] It should be noted that the terms "first", "second", etc. in the description, claims and above-mentioned drawings of the present invention are used to distinguish similar objects, and do not necessarily have to be used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0041] The welding machine mainly welds the strip by welding heat, and the weld seam is the direct result of the welding of the welding machine. Excessive welding heat will cause the strip to be welded through, too little welding heat is likely to result in incomplete penetration, and too large a weld seam thickness is likely to cause weld seam mark defects, while too thin a weld seam thickness is likely to cause the strip to break. Current, speed, and electrode pressure are the main factors affecting the weld seam thickness and effective welding heat. Therefore, there must be a set of welding current, welding speed, and electrode pressure parameters that make the total welding heat and effective heat relatively close, and the weld seam thickness is relatively close to the set value of the weld seam thickness. This set of parameters is the optimal parameters. Therefore, considering the characteristics of the welding machine equipment and welding process comprehensively, an integrated optimization objective function can be established with the goal of maximizing the utilization rate of the total welding heat and the closeness of the calculated weld seam thickness to the set value of the weld seam thickness, so as to solve for the optimal welding current, welding speed, and electrode pressure. By optimizing the electrode pressure, welding speed, and welding current, the welding quality can be improved, which is of great significance for the continuous and efficient production of the continuous annealing unit and the improvement of the surface quality of the strip.

[0042] Example 1:

[0043] The steel grade is ultra-high strength steel 980DP, and the specification is 1300×1.50 mm (width×thickness). The optimization method for the welding process parameters of this ultra-high strength steel includes the following steps:

[0044] Step (A1), collect the welding machine equipment parameters, welding process parameters, and strip parameters, mainly including the thickness h of the forward strip s = 1.5 mm, the thickness h of the backward strip x = 1.5 mm, the width B of the welded strip is 1300 mm, the effective heat calculation coefficient γ when the welding machine welds ultra-high strength steel is 0.2, the penetration rate A is 80%, the strip overlap b d = 1.5 mm, the strip compensation b b = 1 mm, the thickness b of the upper welding wheel hls = 15 mm, the thickness b of the lower welding wheel hlx= 15 mm, the radius of the upper welding wheel is R hls = 160 mm, the radius of the lower welding wheel is R hlx = 160 mm, the elastic modulus of the welding wheel E1 = 118 kN / mm 2 , the Poisson's ratio v1 = 0.35, the pressure of the rolling wheel P N = 2 kN, the influence coefficient ξ of the welding pressure on the thickness of the forward strip s = 20%, the influence coefficient ξ of the pressure on the thickness of the backward strip x = 20%, the welding carbon equivalent of the forward strip Ce1 = 0.5212, the carbon equivalent of the backward strip Ce2 = 0.5212, the specific heat capacity of the strip c = 0.46 J / (g·°C), the density of the strip ρ = 7.85 g / cm 3 , the temperature difference ΔT between the normal temperature and the molten core state of the strip = 1515 °C, the influence coefficient α of the strip thickness on the effective heat = 0.25, the influence coefficient β of the carbon equivalent on the effective heat = 0.2, the melting coefficient of the molten core λ1 = 1.3, the temperature T during strip welding = 1120 °C, the elastic modulus of the strip E2 = 206 kN / mm 2 , the Poisson's ratio v2 = 0.3, the influence coefficient B of the electrode pressure on the weld thickness p = 0.03, the influence coefficient B of the heat on the weld thickness Q = 0.012, the influence coefficient B of the overlap amount on the weld thickness L = 0.08, the minimum current I during strip welding min = 8 KA, the maximum current I during strip welding max = 7 m / min, the minimum welding speed V min = 15 m / min, the maximum welding speed V max = 3 kN, the minimum electrode pressure P min = 25 kN, the maximum electrode pressure P max = 1.5 mm, the set value of the weld thickness H set = 1.5 mm, the total number of times n of collecting parameters for the strip before and after welding one coil = 3;

[0045] Step (B1), define the relevant parameters when the welding machine welds ultra-high strength steel, mainly including the current I during strip welding, the welding speed V, the electrode pressure P, the effective heat Q1 during welding, the total heat Q during welding, the strip welding resistance R, the weld thickness H, the current optimization step size ΔI, the welding speed optimization step size ΔV, the electrode pressure optimization step size ΔP, the optimization objective function G(X), the initial value G(X) of the optimization objective function cs , the number of parameter adjustments i, the parameter adjustment coefficient α i = 0 (i = 1, 2, 3), the optimal value of the welding current I zyj , the optimal value of the welding speed V zyj , the optimal value of the electrode pressure Pzyj , the number of parameter optimization steps j;

[0046] Step (C1), initialize the welding parameter optimization step sizes ΔI = 0.1, ΔV = 0.1, ΔP = 0.1, and the initial value of the objective function G(X) cs = 10 4 , the number of parameter adjustments i = 1; the parameter adjustment coefficient α i = 0 (i = 1, 2, 3), set the number of parameter optimization steps j = 1;

[0047] Step (D1), according to the formula calculate the welding current, welding speed, and electrode pressure I = 17.3KA, V = 12.4m / min, P = 13.8kN;

[0048] Step (E1), according to the model Q = λcA·(ξ s h s + ξ x h x )(b d + b b )ρBΔT calculate the total heat Q = 44378.03J required to form the nugget;

[0049] The heat required to form the nugget at the weld is the heat required for the strip melting of the covered nugget volume. According to the heat calculation formula, a nugget heat calculation model can be obtained, and the total heat Q required to form the nugget during strip welding is calculated by combining the collected relevant parameters;

[0050] Step (F1), according to the model calculate the total resistance when welding ultra-high strength steel as R = 7.91×10 -5 Ω;

[0051] Step (G1), according to the model calculate the effective heat during strip welding as Q1 = 44380.03J;

[0052] The heat used to form the nugget in the total heat is the effective heat, which mainly depends on the total welding resistance and the carbon equivalent of the strip. Based on Joule's law, an effective heat calculation model can be obtained, and the effective heat Q1 during strip welding is calculated by combining the collected relevant parameters;

[0053] Step (H1), according to the model calculate the weld thickness H of the strip as 1.65mm;

[0054] The weld thickness is mainly determined by the pressure of the rolling wheel, the effective welding heat, and the overlap amount of the strip, and there are clear positive and negative correlation relationships. After establishing the weld thickness model, the predicted weld thickness H is calculated according to the collected parameters;

[0055] Step (I1), according to the model Calculate the value of the welding parameter optimization objective function G(X) = 1.04;

[0056] G(X) is a comprehensive function containing three variables I, V, and P. When optimizing one of the parameters, the other two parameters remain unchanged. Therefore, the calculation result of G(X) is a comprehensive value rather than three values. I, V, and P are the main parameters for calculating the effective welding heat Q1 and the predicted weld thickness H. The effective heat Q1 and the predicted weld thickness H are used to calculate the influence function F(X) j of. G(X) is based on the influence function F(X) of welding parameters considering factors such as uniformity and integrity j established, so G(X) is related to I, V, and P, and they are the three basic variables of G(X).

[0057] In the parameter initialization step, a very large initial value G cs (X) has been assigned to G(X). Each calculation result is compared with the initial value. If the calculation result is less than the initial value, the calculation result is assigned to G(X) as the initial value for the next comparison until no more assignment is made, and then G(X) is the minimum value.

[0058] If G(X) > G cs (X) does not hold, then let the parameter adjustment coefficient G cs (X) = G(X), α i = α i +1, and update the values of the welding current, welding speed, or electrode pressure respectively according to the current optimization step size, welding speed optimization step size, and electrode pressure optimization step size. Based on the updated values, perform iterative calculation of G(X) and judge whether G(X) > G cs (X) holds. Each time of calculation, update the values of the welding current, welding speed, or electrode pressure respectively according to the current optimization step size, welding speed optimization step size, and electrode pressure optimization step size. For example, in this calculation, the current is I = I min +α1ΔI, and in the next calculation, it is I = I min +(α1 + 1)ΔI, where ΔI is the current optimization step size, ΔV is the welding speed optimization step size, and ΔP is the electrode pressure optimization step size.

[0059] Step (J1), after judging that G(X) > G cs (X) holds, then enter Step (K1);

[0060] G(X) is a comprehensive function that includes three variables: I, V, and P. The value of i represents the type of optimized parameter. When i = 1, the welding current I is optimized; when i = 2, the welding speed V is optimized; and when i = 3, the electrode pressure P is optimized.

[0061] When optimizing I, V and P remain at their initial values. When the objective function G(X) is minimized, the value of I at this time is the optimal value.

[0062] When optimizing V, I remains at the optimal value and P is at the initial value. When the objective function G(X) is minimized, the value of V at this time is the optimal value.

[0063] When optimizing P, I and V remain at the optimal values. When the objective function G(X) is minimized, the value of P at this time is the optimal value.

[0064] That is, when G(X) is minimized, I, V, and P are the optimal values, completing the optimization of the welding current, welding speed, and electrode pressure.

[0065] Step (K1): After judgment, it is known that i < 3 does not hold, so enter step (L1);

[0066] Step (L1): Assign the optimal values of the welding parameters for this parameter optimization, that is, I zy3 = 17.3 KA, V zy3 = 12.4 m / min, P zy3 = 13.8 kN.

[0067] Step (M1): After judgment, it is known that the number of parameter optimization times j < n does not hold, so enter step (N1)

[0068] Step (N1): Output the optimal welding process parameters I zy3 = 17.3 KA, V zy3 = 12.4 m / min, P zy3 = 13.8 kN.

[0069] In this embodiment, the main parameters in the welding process of ultra-high strength steel 980DP, namely the welding current, welding speed, and electrode pressure, are optimized through the comprehensive optimization objective function. The optimized welding current, welding speed, and electrode pressure can be directly used for the production of ultra-high strength steel 980DP of the same specification, reducing the time for adjusting parameters of the unit and improving the on-site production efficiency.

[0070] Example 2:

[0071] The steel grade is ultra-high strength steel 780Y, and the specification is 1350 × 1.6 mm (width × thickness). The optimization method for the welding process parameters of this ultra-high strength steel includes the following steps:

[0072] Step (A2): Collect the parameters of the welding machine equipment, welding process parameters, and strip parameters, mainly including the thickness h of the forward strip s = 1.6 mm, the thickness h of the rear strip x = 1.6 mm, the width B of the welded strip = 1350 mm, the effective heat calculation coefficient γ of the welding machine when welding ultra-high strength steel = 0.2, the penetration rate A = 80%, the strip overlap b d = 1.5 mm, the strip compensation b b = 1 mm, the thickness b of the upper welding wheel hls = 15 mm, the thickness b of the lower welding wheel hlx = 15 mm, the radius R of the upper welding wheel hls = 160 mm, the radius R of the lower welding wheel hlx = 160 mm, the elastic modulus E1 of the welding wheel = 118 kN / mm 2 、Poisson's ratio v1 = 0.35, the pressure P of the rolling wheel N = 2 kN, the influence coefficient ξ of the welding pressure on the thickness of the forward strip s = 20%, the influence coefficient ξ of the pressure on the thickness of the rear strip x = 20%, the carbon equivalent Ce1 of the forward strip welding = 0.4987, the carbon equivalent Ce2 of the rear strip = 0.4987, the specific heat capacity c of the strip = 0.46 J / (g·°C), the density ρ of the strip = 7.85 g / cm 3 , the temperature difference ΔT between the normal temperature and the nugget state of the strip = 1515 °C, the influence coefficient α of the strip thickness on the effective heat = 0.25, the influence coefficient β of the carbon equivalent on the effective heat = 0.2, the nugget melting coefficient λ1 = 1.3, the temperature T during strip welding = 1120 °C, the elastic modulus E2 of the strip = 206 kN / mm 2 、Poisson's ratio v2 = 0.3, the influence coefficient B of the electrode pressure on the weld thickness p = 0.03, the influence coefficient B of the heat on the weld thickness Q = 0.012, the influence coefficient B of the overlap on the weld thickness L = 0.08, the minimum current I during strip welding min = 8 KA, the maximum current I during strip welding max = 25 KA, the minimum welding speed V min = 7 m / min, the maximum welding speed V max = 15 m / min, the minimum electrode pressure P min = 3 kN, the maximum electrode pressure P max = 25 kN, the set value H of the weld thickness set = 1.6 mm, the total number of times n of collecting parameters for welding a roll of front and rear strips = 3;

[0073] Step (B2): Define the relevant parameters for welding ultra-high-strength steel with a welding machine, mainly including the current I during strip welding, the welding speed V, the electrode pressure P, the effective heat Q1 during welding, the total heat Q during welding, the strip welding resistance R, the weld thickness H, the current optimization step ΔI, the welding speed optimization step ΔV, the electrode pressure optimization step ΔP, the optimization objective function G(X), and the initial value G(X) of the optimization objective function cs , the number of parameter adjustments i, and the parameter adjustment coefficient α i = 0 (i = 1, 2, 3), the optimal value I of the welding current zyj , the optimal value V of the welding speed zyj , the optimal value P of the electrode pressure zyj , the number of parameter optimizations j;

[0074] Step (C2): Initialize the welding parameter optimization steps ΔI = 0.1, ΔV = 0.1, ΔP = 0.1, and the initial value G(X) of the optimization objective function cs = 10 4 , the number of parameter adjustments i = 1; the parameter adjustment coefficient α i = 0 (i = 1, 2, 3), and set the number of parameter optimizations j = 1;

[0075] Step (D2): Calculate the welding current, welding speed, and electrode pressure I = 19KA, V = 10.9m / min, P = 18.9kN according to the formula

[0076] Step (E2): Calculate the total heat Q = 49157.21J required to form a fusion nucleus according to the model Q = λcA·(ξ s h s + ξ x h x )(b d + b b )ρBΔT

[0077] Step (F2): Calculate the total resistance during welding ultra-high-strength steel as R = 6.98×10 Ω according to the model -5 ;

[0078] Step (G2): Calculate the effective heat Q1 = 56204.59J during strip welding according to the model

[0079] Step (H2): Calculate the weld thickness H = 1.61mm of the strip according to the model

[0080] Step (I2): Calculate according to the model ​​​Calculate the objective function value of welding parameter optimization G(X) = 1.09;

[0081] Step (J2), after judging that G(X) > G cs (X) holds, then enter Step (K2);

[0082] Step (K2), after judging that i < 3 does not hold, then enter Step (L2);

[0083] Step (L2), assign the optimal value of the welding parameters for this parameter optimization, that is, I zy3 = 19KA, V zy3 = 10.9m / min, P zy3 = 18.9kN;

[0084] Step (M2), after judging that the number of parameter optimization times j < n does not hold, then enter Step (N2);

[0085] Step (N2), output the optimal welding process parameters I zy3 = 19KA, V zy3 = 10.9m / min, P zy3 = 18.9kN.

[0086] In Example 1, the welding parameters for welding ultra-high strength steel 980DP were optimized. In this example, the main parameters in the welding process of ultra-high strength steel 780Y, namely welding current, welding speed, and electrode pressure, were optimized through a comprehensive optimization objective function, ensuring the weld quality during the production of ultra-high strength steel 780Y, reducing the strip breakage rate during the production process of the unit, and greatly improving the production efficiency of the unit.

[0087] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for optimizing welding process parameters suitable for ultra-high strength steel, characterized in that, Including the following steps executed by a computer: Calculating the welding current I, the welding speed V, and the electrode pressure P; Establishing a comprehensive optimization objective function G(X) = ωφ1(X) + (1 - ω)φ2(X) with the goal of maximizing the utilization rate of the total welding heat and the proximity of the calculated weld thickness to the set value of the weld thickness; Among them, ω is the weighting coefficient of the welding parameter optimization objective function; X = {I, V, P}; φ1(X) and φ2(X) are process functions, F(X) j is the influence function of welding parameters, is the influence ratio of welding heat and weld thickness on the influence function, Q1 is the effective heat during welding, Q is the total heat during welding, H is the weld thickness, H set is the set value of weld thickness, j is the number of parameter optimization; is the average value of the influence function, n is the total number of parameters collected for the strip before and after welding a roll; I is the current during strip welding, I min ≤I≤I max , V is the welding speed, V min ≤V≤V max , P is the electrode pressure, P min ≤P≤P max ; I min is the minimum current during strip welding, I max is the maximum current during strip welding, V min is the minimum welding speed, V max is the maximum welding speed, P min is the minimum electrode pressure, P max is the maximum electrode pressure; Solving for the minimum value of the comprehensive optimization objective function to obtain the optimal welding current, welding speed, and electrode pressure, including: Determine whether G(X) > G cs (X) holds, where G cs (X) is the initially set objective function value; If G(X) > G cs (X) does not hold, then set the parameter adjustment coefficient G cs (X) = G(X), α i = α i + 1, update the values of the welding current, welding speed, and electrode pressure respectively according to the current optimization step size, welding speed optimization step size, and electrode pressure optimization step size, and perform iterative calculation of G(X) and determine whether G(X) > G cs (X) holds based on the updated values; If G(X) > G cs (X) holds, determine whether the number of optimized parameters i < 3 holds; If the number of optimized parameters i < 3 holds, then set i = i + 1 and return to the step of calculating the welding parameters I, V, P to optimize the next variable; when i = 1, optimize the welding current I, when i = 2, optimize the welding speed V, and when i = 3, optimize the electrode pressure P; If it does not hold that the number of optimized parameters \(i < 3\), then assign values to the optimal parameter values for the current parameter optimization, that is, \(I\) zyj = \(I\), \(V\) zyj = \(V\), \(P\) zyj = \(P\), \(I\) zyj is the optimal value of the welding current, \(V\) zyj is the optimal value of the welding speed, \(P\) zyj is the optimal value of the electrode pressure.

2. A method for optimizing welding process parameters suitable for ultra-high strength steel according to claim 1, characterized in that, Return to the step of calculating the welding parameters I, V, P to optimize the next variable, including: When optimizing I, keep the initial values of V and P unchanged. When the objective function G(X) is minimized, the value of I at this time is the optimal value; When optimizing V, keep the optimal value of I unchanged and P as the initial value. When the objective function G(X) is minimized, the value of V at this time is the optimal value; When optimizing P, keep the optimal values of I and V unchanged. When the objective function G(X) is minimized, the value of P at this time is the optimal value.

3. A method for optimizing welding process parameters suitable for ultra-high strength steel according to claim 1, characterized in that, It also includes: Judge whether j < n holds. If j < n holds, let j = j + 1 and enter the next parameter optimization process. If j < n does not hold, output the currently optimized optimal welding process parameters I zyj 、V zyj 、P zyj 。 4. A method for optimizing welding process parameters suitable for ultra-high strength steel according to claim 1, characterized in that Calculating the total heat required to form a fusion nucleus during welding, including: According to the formula Q = λcA·(ξ s h s + ξ x h x )(b d + b b )ρBΔT, calculate the total heat Q required to form the nugget; Among them, λ is the fusion coefficient of the nugget, c is the specific heat capacity of the strip, A is the penetration rate, h s is the thickness of the forward strip, h x is the thickness of the backward strip, ξ s is the influence coefficient of the electrode pressure on the thickness of the forward strip, ξ x is the influence coefficient of the electrode pressure on the thickness of the backward strip, b d is the overlap amount of the strip, b b is the compensation amount of the strip, B is the width of the strip to be welded, ρ is the density of the strip, and ΔT is the temperature difference between the normal temperature of the strip and the state of the nugget.

5. The optimization method of welding process parameters suitable for ultra-high strength steel according to claim 4, characterized in that Calculating the effective heat of strip welding, including: According to the formula Calculate the effective heat Q1 for strip welding; Where t is the welding time of the welder for the strip steel, γ is the effective heat calculation coefficient when the welder welds ultra-high strength steel, Ce1 is the welding carbon equivalent of the forward strip steel, Ce2 is the carbon equivalent of the rear strip steel, R is the total resistance when welding ultra-high strength steel, α is the influence coefficient of the strip thickness on the effective heat, and β is the influence coefficient of the carbon equivalent on the effective heat.

6. The optimization method of welding process parameters suitable for ultra-high strength steel according to claim 5, characterized in that, Calculating the total resistance R when welding ultra-high strength steel, including: According to the formula Calculate the total resistance R when welding ultra-high strength steel; Among them, m is the strip contact coefficient, K c is a coefficient related to the contact material, surface condition, and contact form. ρ0 is the resistivity value of the strip at 0°, ρ0 = 9.78×10 -8 Ωm, α1 is the influence coefficient of temperature on resistivity, T is the temperature during strip welding, E2 is the elastic modulus of the strip, v2 is the Poisson's ratio, b hls is the thickness of the upper welding wheel, b hlx is the thickness of the lower welding wheel, R hls is the radius of the upper welding wheel, R hlx is the radius of the lower welding wheel, E1 is the elastic modulus of the welding wheel, and v1 is the Poisson's ratio.

7. A method for optimizing welding process parameters suitable for ultra-high strength steel according to claim 1, characterized in that, Calculating the weld thickness of the strip, including: According to the formula calculate the weld thickness H of the strip; Among them, P N is the rolling wheel pressure, B p is the influence coefficient of the electrode pressure on the weld thickness, B Q is the influence coefficient of the heat on the weld thickness, b d is the strip overlap amount, b b is the strip compensation amount, B L is the influence coefficient of the overlap amount on the weld thickness.

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