A method and system for controlling the forming and welding of spiral welded steel pipes

Abstract

This invention provides a welding control method and system for spiral welded steel pipe forming, relating to the field of welding control technology. Addressing the problems of poor adjustment efficiency leading to poor welding stability and high energy consumption in the current submerged arc welding process for welded steel pipes, this invention effectively combines welding experience values, heat conversion efficiency, actual welding parameters, and the characteristics of weld appearance and performance. It determines welding parameters and continuously corrects these parameters during the welding process, providing guidance and application for actual production, thereby improving welding stability and reducing welding energy consumption.

Description

Technical Field

[0001] This invention relates to the field of welding control technology, specifically to a welding control method and system for spiral welded steel pipe forming. Background Technology

[0002] Corrosion-resistant steel pipes are widely used as transportation channels, and within the entire steel pipe product series, spiral welded steel pipes are the main type for pipes with a diameter of DN300mm and above. Spiral welded steel pipes are made by rolling steel strips or plates into shape using a spiral mill, followed by online welding, hydrostatic testing, X-ray or ultrasonic testing, repair, and end-pressing / beveling. This type of pipe has been widely promoted and applied in the industry due to its advantages of low cost, high safety factor, and high production efficiency.

[0003] Although spiral welded pipe production lines are upgrading rapidly and becoming increasingly automated, the submerged arc welding process remains a major bottleneck hindering production and proving difficult to resolve. Submerged arc welding requires real-time adjustments based on welding conditions and raw material conditions. However, current adjustment methods heavily rely on welder operation, making them highly susceptible to human error. While some control and adjustment methods are disclosed in existing technologies, their real-time adjustment efficiency during correction is poor, resulting in poor welding stability and high welding energy consumption, severely restricting production efficiency and product quality. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a spiral welded steel pipe forming welding control method and system. This method effectively combines welding experience values, heat conversion efficiency, actual welding parameters, and the characteristics of weld appearance gears and performance to determine welding parameters and continuously correct these parameters during the welding process. This provides guidance and application for actual production, improves welding stability, and reduces welding energy consumption.

[0005] The first objective of this invention is to provide a method for controlling the forming and welding of spiral welded steel pipes, which employs the following approach:

[0006] The cross-sectional area of ​​the weld is calculated based on the weld shape, and the theoretical heat required for the weld to melt is calculated in combination with the welding speed and steel pipe parameters;

[0007] Set the welding current and welding voltage, obtain the welding energy, and compare the welding energy with the theoretical heat.

[0008] When the ratio of welding energy to theoretical heat is not within the set range, adjust the welding current and welding voltage until the ratio of welding energy to theoretical heat is within the set range.

[0009] Furthermore, the width and depth of the weld are determined based on the wall thickness and raw material specifications of the welded steel pipe, thereby determining the weld shape and calculating the weld cross-sectional area.

[0010] Furthermore, the weld depth is the depth of the molten pool during welding, and its size is smaller than the wall thickness of the steel pipe to avoid burn-through, and greater than or equal to 0.6 times the wall thickness of the steel pipe to ensure its welding strength.

[0011] Furthermore, calculating the theoretical heat required for weld melting includes the following steps:

[0012] Obtain the temperature difference between the initial temperature and the welding melting temperature of the steel pipe;

[0013] Calculate the weight of the weld area per unit length based on the weld cross-sectional area, welding speed, and welding wire density;

[0014] The theoretical heat required for weld melting is calculated by combining the temperature difference and the weight of the weld area.

[0015] Furthermore, the density of the welding wire is the same as that of the steel pipe.

[0016] Furthermore, an effective coefficient for welding power is set, with the effective coefficient ranging from 0.75 to 0.85.

[0017] Furthermore, when adjusting the welding current, the minimum value of the obtained correction range is selected sequentially upwards until the welding energy requirement is met.

[0018] Furthermore, the welding current value is determined based on the steel pipe wall thickness, welding wire diameter, and empirical values.

[0019] Furthermore, the welding voltage value is determined based on the welding current and the welding wire diameter coefficient.

[0020] A second objective of this invention is to provide a spiral welded steel pipe forming and welding control system, comprising:

[0021] The theoretical data acquisition module is configured to: calculate the cross-sectional area of ​​the weld based on the weld shape, and calculate the theoretical heat required for the weld to melt by combining the welding speed and steel pipe parameters;

[0022] The comparison module is configured to: set the welding current and welding voltage, obtain the welding energy, and compare the welding energy with the theoretical heat.

[0023] The adjustment module is configured to adjust the welding current and welding voltage until the ratio of welding energy to theoretical heat is within the set range when the ratio is not within the set range.

[0024] Compared with the prior art, the advantages and positive effects of this invention are:

[0025] (1) In view of the problem that the control and adjustment process of submerged arc welding of steel pipes is poor, resulting in poor welding stability and high energy consumption, welding parameters are determined by effectively combining welding experience value, heat conversion efficiency, actual welding parameters and the characteristics of welding appearance gear and performance. The parameter values ​​are continuously corrected during the welding process for guidance and application in actual production, thereby improving welding stability and reducing welding energy consumption.

[0026] (2) Substitute the welding parameter values ​​into the formula for correction. Select the welding current from the minimum value to the maximum value until the requirement is met. This can satisfy the requirements of the weld pool depth and width during welding, forming a weld that meets the strength and shape requirements. It can also reduce welding energy consumption by reducing the welding current. Attached Figure Description

[0027] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0028] Figure 1 This is a schematic diagram of the weld cross-section in submerged arc welding according to Embodiment 1 of the present invention. Detailed Implementation

[0029] Example 1

[0030] In a typical embodiment of the present invention, such as Figure 1 As shown, a method for controlling the forming and welding of spiral welded steel pipes is presented.

[0031] Currently, in spiral welded steel pipe production lines, steel strips or plates are rolled into shape by spiral units and then welded using submerged arc welding. Real-time adjustments are required based on the welding status and the condition of the raw materials. However, current adjustment methods largely depend on the operation of the welders and are greatly affected by human factors. Although some related control and adjustment methods have been disclosed in existing technologies, their real-time adjustment efficiency during the correction process is poor, resulting in poor welding stability and high welding energy consumption.

[0032] Based on this, this embodiment provides a spiral welded steel pipe forming welding control method. By effectively combining welding experience values, heat conversion efficiency, actual welding parameters, and the characteristics of welding appearance gears and performance, welding parameters are determined and continuously corrected during the welding process. This method is used for guidance and application in actual production, improving welding stability and reducing welding energy consumption.

[0033] The above-mentioned spiral welded steel pipe forming and welding control method will be described in detail below with reference to the accompanying drawings.

[0034] See Figure 1Based on the forming principle of spiral steel pipe, the forming speed and the welding speed are correlated digitally; the welding principle is combined with the geometric dimensions of the weld, and the welding filler volume is calculated according to the principle of mass conservation; based on the principle of mass conservation and combined with the efficiency of actual energy conversion, the total energy demand is calculated using the specific heat capacity of the steel pipe; based on actual welding experience and welding requirements, the required welding shape is fixed, data is measured by sensors, and the measured data can be transmitted.

[0035] By combining the above data, a model for calculating welding parameters is established to achieve automatic control of welding parameters during the spiral welded steel pipe forming process. This results in automated welding parameters and stable welding quality.

[0036] In the process of forming and welding spiral welded steel pipes, the important parameters of the welding process include welding current and welding voltage, where welding current is represented by I1 and welding voltage by V1. The direct factors affecting the forming and welding process are mainly forming speed, steel plate thickness, bevel angle, and welding wire diameter.

[0037] Known process parameters in actual production include: outer diameter of steel pipe (D0), wall thickness of steel pipe (t), density of steel pipe (ρ1), initial temperature of steel pipe (T1), plate feed rate (v3), wire diameter (d1), wire density (ρ2), required width of weld (B1), weld reinforcement (h1), and welding melting temperature (T2).

[0038] The weld width requirement B1 is 10mm, and the weld reinforcement height h1 is 2.5mm.

[0039] Unknown process parameters in actual production include: welding current (I1), welding voltage (V1), weld cross-sectional area (S1), welding speed (v2), welding power (P), welding power efficiency coefficient (η), theoretical heat required for welding (Q), welding time (t2), total welding weight (M), welding weight (M1), and specific heat capacity of steel plate (ρ).

[0040] The outer diameter of the steel pipe, the wall thickness of the steel pipe, the density of the steel pipe, and the density of the welding wire are known parameters;

[0041] The temperature difference between the initial temperature T1 and the welding melting temperature T2 of the steel pipe is: ΔT = T2 - T1;

[0042] The energy required to heat a steel pipe from its initial temperature to its welding melting temperature T2 is: Q = MΔT;

[0043] Based on practical production experience, the effective coefficient of welding power η ranges from 0.75 to 0.85.

[0044] Welding power: P = I1 * V1.

[0045] Using the above data, determining welding parameters that conform to actual production is the foundation of welding control methods. Among them, the relationship between welding current and voltage is a law obtained by combining theoretical calculations with actual production conditions. What can be used to guide production is the difference between the total energy required for the weld and the actual welding energy during the forming welding process, in order to control and adjust the total welding power and the actual current and voltage parameters.

[0046] By combining theoretical calculations with actual welding conditions, welding parameters are corrected to achieve real-time adjustment. In this embodiment, the spiral welded steel pipe forming welding control method includes:

[0047] The cross-sectional area of ​​the weld is calculated based on the weld shape, and the theoretical heat required for the weld to melt is calculated in combination with the welding speed and steel pipe parameters;

[0048] Set the welding current and welding voltage, obtain the welding energy, and compare the welding energy with the theoretical heat.

[0049] When the ratio of welding energy to theoretical heat is not within the set range, adjust the welding current and welding voltage until the ratio of welding energy to theoretical heat is within the set range.

[0050] The width and depth of the weld are determined based on the wall thickness and raw material specifications of the welded steel pipe, thereby determining the weld shape and calculating the weld cross-sectional area. Different welding widths and depths are configured for different specifications of raw materials, resulting in different weld cross-sectional areas.

[0051] In this embodiment, the weld depth is the depth of the molten pool during welding. Its size is smaller than the wall thickness of the steel pipe to avoid burn-through, and greater than or equal to 0.6 times the wall thickness of the steel pipe to ensure its welding strength.

[0052] According to the forming principle: v3 = v2. The penetration depth H is linearly related to the welding current I1: H = k / 100 * I1; based on experience, the value of k is generally taken as 1.1.

[0053] Based on experience, the welding current I1 = 40*t + 50d1 + 50; the welding voltage V1 = 30 + I1 / 100 + C, where C is the welding wire diameter coefficient; the welding penetration depth must be no less than 0.6 times the steel pipe wall thickness, i.e., 0.6t ≤ H ≤ 0.7t; the weld cross-sectional area S1 is as follows: Figure 1 As shown. Alternatively, the welding current I1 = 28(t+10) and the welding voltage V1 = 0.5t+30 can be configured.

[0054] The configuration parameters are shown in Table 1:

[0055] Table 1. Applicable welding currents for different diameter welding wires.

[0056]

[0057] When the welding wire is Φ5mm, C is 1; when the welding wire is Φ4mm, C is 2; when the welding wire is Φ3mm, C is 2.

[0058] The welding penetration depth is determined based on time-based production experience parameters. The weld width and height are actual measured values. In addition, the welding melting temperature is an actual measured value, not a calculated value, and needs to be adjusted according to the welding melting temperature.

[0059] The total weight of the weld area is M = S1 * v2 * ρ1; the density of the welding wire is the same as the density of the steel plate.

[0060] The theoretical heat required for the weld to melt is Q = MΔT = ρ*S1*v2*t2*ρ1*ΔT;

[0061] Welding power: P=I1*V1; and P*t2*η=Q, that is: I1*V1*t2*η=ρ*S1*v2*t2*ρ1*ΔT; I1*V1*η=ρ*S1*V2*ρ1*ΔT;

[0062] Welding current I1 = H / k * 100; I1 = 40 * t + 50d1 + 50; therefore: H / k = 40 * t + 50d1 + 50; based on actual production experience, k is taken as 1.1, and H is taken as 0.6t and 0.7t respectively;

[0063] The welding wire diameters are d1 = (14.5t - 50) / 50 and d1 = (23.6t - 50) / 50 respectively;

[0064] Welding current: I1 = H / k * 100 = 54.5t - 63.6t;

[0065] The welding wire diameter is selected from four values: 3, 4, 4.5, and 5. Furthermore, a smaller welding current is generally chosen to reduce energy consumption.

[0066] Welding voltage: V1=30+I1 / 100+C; therefore, the voltage value is V1=30+0.545t+C / 30+0.636t+C;

[0067] Once the welding current and voltage are determined, the welding power is: P = I1 * V1;

[0068] That is: P = (30 + I1 / 100 + C) * I1; Welding energy Q1 = P * t2 = (30 + I1 / 100 + C) * I1 * t2

[0069] Furthermore, based on the principle that welding energy Q1 * effective efficiency η ≥ theoretical heat Q required for weld melting, and combined with actual welding experience, welding energy Q1 * effective efficiency η < (1 + 0.15) * theoretical heat Q required for weld melting.

[0070] Therefore: 1.15*ρ*S1*v2*ρ1*ΔT≥(30+I1 / 100+C)*I1*t2*η≥ρ*S1*v2*ρ1*ΔT; Thus, the welding parameter values ​​are substituted into this formula for correction, and the welding current is selected sequentially from the minimum value upwards until the requirement is met.

[0071] For example: when welding a pipe with a wall thickness of 10mm, the weld width is 10mm; the average temperature during welding is T2 = 6500℃; the ambient temperature is T1 = 25℃; the specific heat capacity of the steel is 480J / (kg·℃); the density of the steel is 7.85g / cm³. 3 Welding cross-sectional area S1 = 42 mm 2 The welding speed v2 = 1.2 m / min, therefore the theoretical heat required for weld melting is Q = 122.96 J / mm². 2 ;

[0072] Combining the first empirical formula: welding time t2 = 1 / v2, current I1 is between 545-636 J / mm², let's take 545 J / mm², then C is 2, so V1 = (30 + I1 / 100 + C) = 37.45 J / mm², and η is 0.8; therefore, welding energy Q1 * effective efficiency η = 136.06 J / mm². 2 ; 1.15*122.96J / mm 2 ≥136.06J / mm 2 >122.96J / mm 2 Therefore, a current of 545V and a voltage of 37.45V are sufficient to meet a welding speed of 1.2m / min. Combining this with the second empirical formula: I1 = 560, V1 = 35, the welding energy Q1 * effective efficiency η = 130.66J / mm². 2 ; 1.15*122.96J / mm 2 ≥130.66J / mm 2 >122.96J / mm 2 Therefore, a current value of 560 Ω and a voltage value of 35 Ω can meet the welding requirements. Combining two empirical formulas, the current process parameter value is 545-560 Ω, and the voltage process parameter value is 35-37.5 Ω. The welding parameters are shown in Table 2.

[0073] Table 2 Data Comparison

[0074]

[0075] During the welding process, the system continuously inputs and corrects the current and voltage; in conjunction with the actual welding process, it ensures stable welding quality, and the current value is adjusted by increasing it sequentially according to the minimum requirements, which also achieves energy-saving effect.

[0076] Example 2

[0077] In another embodiment of the present invention, a spiral welded steel pipe forming and welding control system is provided.

[0078] include:

[0079] The theoretical data acquisition module is configured to: calculate the cross-sectional area of ​​the weld based on the weld shape, and calculate the theoretical heat required for the weld to melt by combining the welding speed and steel pipe parameters;

[0080] The comparison module is configured to: set the welding current and welding voltage, obtain the welding energy, and compare the welding energy with the theoretical heat.

[0081] The adjustment module is configured to adjust the welding current and welding voltage until the ratio of welding energy to theoretical heat is within the set range when the ratio is not within the set range.

[0082] It is understood that the working method of the spiral welded steel pipe forming and welding control system described above is the same as the spiral welded steel pipe forming and welding control method provided in Example 1. Please refer to the detailed description in Example 1 above, which will not be repeated here.

[0083] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method of controlling the forming and welding of a spiral welded steel pipe, characterized by, The application relates to a welding parameter automatic adjustment method and device. The welding parameters are determined by effectively combining welding experience values, heat conversion efficiency, welding actual parameters and the characteristics of welding appearance gears and performance, and the parameter values are continuously corrected in the welding process; The welding seam section area is calculated according to the welding seam shape, and the theoretical heat required for welding seam melting is calculated by combining the welding speed and the steel pipe parameters; The welding energy is obtained by setting the welding current and the welding voltage, and the welding energy and the theoretical heat are compared; When the ratio of the welding energy to the theoretical heat is not in the set range, the welding current and the welding voltage are adjusted until the ratio of the welding energy to the theoretical heat is in the set range; the determination process comprises the following steps: according to the welding energy Q1*effective coefficient eta >= the theoretical heat required for welding seam melting Q; combining the actual welding experience, the welding energy Q1*effective coefficient eta < (1+0.15)*the theoretical heat required for welding seam melting Q; that is, 1.15*P*S1*v2*P1*Delta T >= (30+I1 / 100+C)*I1*t2*eta >= P*S1*v2*P1*Delta T; when the welding current is adjusted, the welding parameter value is brought into the formula for correction, the welding current is selected from the minimum value upwards in sequence until the welding energy requirement is met; wherein the welding current is I1=H / k*100=54.5t-63.6t; the welding voltage is V1=30+I1 / 100+C; the effective coefficient of the set welding power is in the range of 0.75-0.85; the welding time t2=1 / v2; Wherein P is the specific heat capacity of the steel plate; S1 is the welding seam section area; v2 is the welding speed; P1 is the steel pipe density; Delta T is the temperature difference of the steel pipe heated from the initial temperature T1 to the welding melting temperature T2, Delta T=T2-T1; C is the welding wire diameter coefficient; H is the penetration; k is the penetration coefficient, and the k value is generally taken as 1.1 in combination with experience; t is the wall thickness of the steel pipe.

2. The helical weld steel pipe forming and welding control method as recited in claim 1, characterized by, The welding seam shape is determined according to the wall thickness of the welded steel pipe and the material specification, so as to calculate the welding seam section area.

3. The helical weld steel pipe forming and welding control method as recited in claim 2, characterized by, The welding seam depth is the penetration of the molten pool during welding, and the size is smaller than the wall thickness of the steel pipe to avoid burning through, and is greater than or equal to 0.6 times the wall thickness of the steel pipe to ensure the welding strength.

4. The helical weld steel pipe forming and welding control method as recited in claim 1, characterized by, The theoretical heat required for welding seam melting comprises the following steps: The temperature difference of the steel pipe heated from the initial temperature to the welding melting temperature is obtained; The welding seam area weight per unit length is calculated based on the welding seam section area, the welding speed and the welding wire density; The theoretical heat required for welding seam melting is calculated by combining the temperature difference and the welding seam area weight.

5. The helical weld steel pipe forming and welding control method as recited in claim 1, characterized by, The density of the welding wire is consistent with the density of the steel pipe.

6. A spiral-welded steel pipe forming and welding control system employing the spiral-welded steel pipe forming and welding control method according to any one of claims 1 to 5, characterized by The application further discloses a welding parameter automatic adjustment device. The theoretical data acquisition module is configured to calculate the welding seam section area according to the welding seam shape, and calculate the theoretical heat required for welding seam melting by combining the welding speed and the steel pipe parameters; The comparison module is configured to set the welding current and the welding voltage, obtain the welding energy, and compare the welding energy and the theoretical heat; The adjustment module is configured to adjust the welding current and the welding voltage when the ratio of the welding energy to the theoretical heat is not in the set range, until the ratio of the welding energy to the theoretical heat is in the set range.

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