Large-gap steel structure gradient magnetic control collaborative welding process

Abstract

The present application relates to the technical field of welding production, in particular to a large-gap steel structure gradient magnetic control collaborative welding process, which comprises the following steps: a step gradient wire feeding frame is built from bottom to top along the welding thickness direction in the welding large gap of a workpiece to be welded; a double-welding-head welding gun head is arranged above the wire feeding frame, and a magnetic exciting coil is installed on the welding gun head; an alternating transverse magnetic field is generated after starting to drive the first electric arc and the second electric arc to swing synchronously along the width direction of the welding large gap, and the workpiece side wall and the wire feeding sheet side wall are alternately melted in the swinging stroke; the welding gun head travels along the welding direction, and the large-gap welding is completed at one time. The double-welding-head synchronous welding is arranged, and compared with the single-welding-gun serial welding, the welding time is saved; the extremely narrow gap between the wire feeding sheet and the base material side wall can effectively melt the surfaces on both sides at the same time, the magnetic control swinging is combined to ensure that the side wall is uniformly heated, and the problems of low welding efficiency and complex control of the large-gap steel structure welding are solved.

Description

Technical Field

[0001] This invention relates to the field of welding production technology, specifically to a gradient magnetic control synergistic welding process for large-gap steel structures. Background Technology

[0002] Patent No. CN120347334B discloses a closed-loop pulsed GTAW large-gap weld system and method based on vision-arc perception. This technology addresses the adverse effects of welding wire, welding torch, and arc deviations on weld formation in large-gap GTAW welding, and proposes a closed-loop pulsed GTAW large-gap weld system. The system consists of a GTAW robot, a vision system, a welding torch system, a welding wire system, and a central control system. The central control system controls the GTAW robot to ignite the arc and simultaneously acquires arc signals. It implements closed-loop adjustment of the arc length through arc and vision signals. When the vision system detects that the base metal has reached a molten state, it controls the welding wire system to deliver filler metal to the molten pool. After the molten droplet transfer is complete, the arc is extinguished, and the welding torch is moved to the next arc ignition point. This cycle continues in units of one pulse period.

[0003] Simply put, existing technology uses pulsed arc initiation, wire feeding, melting at one point, breaking the arc, and then moving to the next point, repeating the process. During the process, a vision sensor takes real-time photos, and the gap size is identified by image recognition to calculate where to weld, how many points to weld, and how much wire to feed.

[0004] It is evident that existing technologies are inefficient and complex to control. Several layers of weld points need to be arranged along the thickness direction, and the gaps and number of points in each layer must be calculated visually, which places high demands on the system and mechanical precision. In addition, visual sensors are unreliable on construction sites; the steel structure sites of buildings and bridges are characterized by a lot of smoke, dust, and arc light, which can easily make the lenses dirty and cause unstable imaging. Once a problem is found in visual recognition, the entire closed-loop welding will be disrupted. Summary of the Invention

[0005] The problem this invention aims to solve is: can we abandon this complex vision closed-loop system and adopt a different continuous welding method that allows the welding torch to fill the entire large gap in a single stroke, while ensuring that the sidewalls are thoroughly welded and firmly fused?

[0006] In order to overcome the defects in the prior art, the purpose of this invention is to provide a gradient magnetic control synergistic welding process for large-gap steel structures to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, this invention provides a gradient magnetic control co-welding process for large-gap steel structures, including the preparation and installation of a stepped gradient filler wire frame, the setup of the welding device, and magnetic control oscillating welding; specifically, it includes the following steps: S1. Within the large gap of the workpiece to be welded, at least two steps are erected sequentially from bottom to top along the welding thickness direction to form a stepped gradient wire feeder. Each step consists of a wire feeder sheet. Each wire feeder sheet extends continuously in the welding direction and leaves a gap b between itself and the side wall of the base material on the side closest to the base material side wall, where 0.5mm≤b≤2.5mm. This gap width falls within the normal applicable range of conventional MAG / CO2 welding process, which can ensure that the arc can smoothly melt the sidewall of the filler wire sheet and the sidewall of the base material, fundamentally avoiding the physical bottleneck that large gaps cannot be directly welded. S2. A welding torch head is set above the filler wire holder. The welding torch head extends a first welding head and a second welding head at intervals along the large gap width direction. The first welding head corresponds to the first filler wire step, and the second welding head corresponds to the second filler wire step. An excitation coil is installed on the welding torch head. The excitation coil surrounds the conductive tip of the first welding head and the conductive tip of the second welding head at the same time, and is used to synchronously generate an alternating transverse magnetic field in the arc area of ​​the first welding head and the arc area of ​​the second welding head. The excitation coil generates an alternating transverse magnetic field along the weld width direction, which acts synchronously on the two electric arcs, driving them to make coordinated reciprocating oscillating motions along the weld width direction with the same frequency and phase. S3. A first welding wire is fed into the first welding head and the first electric arc is ignited. A second welding wire is fed into the second welding head and the second electric arc is ignited. Simultaneously, an excitation current is fed into the excitation coil to generate an alternating transverse magnetic field that drives the first and second electric arcs to swing synchronously along the width of the welding gap. This causes the first and second electric arcs to alternately melt the sidewall of the workpiece and the sidewall of the filler wire sheet of the corresponding step within their swing stroke. Driven by the magnetic field, the electric arcs alternately sweep across the sidewall of the base material and the sidewall of the filler wire sheet within their swing stroke, so that the base material and the filler wire sheet melt and fuse synchronously during the welding process. S4. The welding torch head moves along the weld direction, and the first welding head and the second welding head weld simultaneously. Within a single welding stroke, each filler piece of the stepped gradient filler wire frame and the filled welding wire are melted together and re-solidified to form a shape, thus completing the filling of the large gap weld in one go.

[0008] This invention employs a single excitation coil simultaneously encircling two welding heads, treating the dual arcs as a unified welding unit for overall driving. The resulting alternating magnetic field exerts synchronous, unidirectional, and equal-amplitude electromagnetic forces on the two arcs, without introducing additional disturbance components. The welding currents of the two parallel welding wire arcs flow in the same direction, both from the welding wire to the base material. The unidirectional currents generate mutually attractive Ampere forces, which draw the two arcs closer together, forming a more concentrated unified heat source—a phenomenon known as the "synergistic heat concentration effect" between the arcs. This effect not only avoids harmful magnetic blow but also facilitates the rapid establishment and stable maintenance of the molten pool.

[0009] As a further improvement to this technical solution, in step S1, the stepped gradient filler frame includes a first filler sheet and a second filler sheet that overlap sequentially from bottom to top. The width W1 of the first filler sheet and the width W2 of the second filler sheet satisfy: W1 > W2, so that the overall outer contour of the filler frame shrinks in a stepped shape along the welding thickness direction; the thickness of each filler sheet is 1.5 to 3.0 mm.

[0010] As a further improvement to this technical solution, in step S1, the material of the filler sheet is the same as or belongs to the same grade series as the base material to be welded, and the allowable deviation of the chemical composition of the filler sheet from that of the base material meets the requirements of the corresponding grade in GB / T1591 or GB / T19879.

[0011] As a further improvement to this technical solution, in step S2, the distance L between the first welding head and the second welding head in the welding travel direction is 5 to 20 mm, and the distance H in the welding thickness direction is 3 to 10 mm.

[0012] As a further improvement to this technical solution, in step S2, the excitation coil surrounds the outer periphery of the welding torch head, and the conductive tips of the first welding head and the second welding head are both located in the inner cavity surrounded by the excitation coil; the excitation coil generates an alternating transverse magnetic field with a peak magnetic induction intensity B of 5 to 30 mT in the arc region, and the excitation current frequency f is 1 to 20 Hz.

[0013] As a further improvement to this technical solution, in step S3, both the first welding head and the second welding head adopt CO2 gas shielded welding or gas metal arc shielded welding, the shielding gas is 100% CO2 or Ar+CO2 mixed gas, the welding current is 160~350A, and the arc voltage is 22~36V.

[0014] As a further improvement to this technical solution, the first and second welding heads adopt a pulse welding mode with a pulse frequency of 2 to 8 Hz, and the pulse periods of the two welding heads are kept synchronized; the difference in welding current between the first and second welding heads does not exceed 30A.

[0015] As a further improvement to this technical solution, in step S1, the thickness of the base material to be welded is 10-60mm, and the width of the large gap is 5-20mm.

[0016] As a further improvement to this technical solution, in step S3, the swaying amplitude of the first and second electric arcs driven by the alternating transverse magnetic field is 3 to 15 mm, covering the gap area between the sidewall of the filler sheet and the sidewall of the base material.

[0017] As a further improvement to this technical solution, the welding torch head and the excitation coil are integrated on the robotic arm of the automated welding carriage or welding manipulator, and the welding speed is 200-500 mm / min.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The gradient magnetic control collaborative welding process for large-gap steel structures saves welding time compared to single-gun serial welding by using dual welding heads for synchronous welding. The extremely narrow gap between the filler wire sheet and the side wall of the base material allows the electric arc to effectively melt both sides of the surface at the same time. Combined with magnetic control oscillation, it ensures that the side wall is heated evenly, fundamentally solving the technical problem of interlayer non-fusion in the prefabricated filler block embedding scheme.

[0019] 2. The gradient magnetic control collaborative welding process for large-gap steel structures features a simple structure with a single excitation coil driving a dual-arc device. It is easy to control, has strong anti-interference capabilities, and is suitable for stable operation in harsh construction site environments.

[0020] 3. This gradient magnetic control collaborative welding process for large-gap steel structures can be adapted to welding conditions with different plate thicknesses and gap widths by flexibly adjusting the step height of the filler wire and the spacing of the welding heads. Attached Figure Description

[0021] The accompanying drawings described herein are for illustrative purposes only. The shapes and proportions of the components in the drawings are merely schematic and intended to aid in understanding the invention. They are not intended to specifically limit the shapes and proportions of the components of the invention.

[0022] Figure 1 This is a flowchart of the welding process of the present invention; Figure 2 The following are comparative bar charts showing the weld tensile strength comparison of embodiments and comparative examples of the present invention; Figure 3 The following are comparative bar charts showing the weld porosity comparison of embodiments and comparative examples of the present invention; Figure 4 The above are bar charts comparing the fusion degree of welded sidewalls in the embodiments and comparative examples of the present invention. Detailed Implementation

[0023] The specific embodiments described herein are for illustrative purposes only. Under the guidance of this invention, any possible variations of the invention by those skilled in the art should be considered within its scope. The directional terms used herein are based on the orientations shown in the accompanying drawings and are for ease of description and simplification; therefore, they should not be construed as limitations on the invention. Furthermore, in the description of this invention, "a number" means two or more, unless otherwise explicitly specified.

[0024] Please see Figures 1-4 As shown, this invention provides a gradient magnetic control co-welding process for large-gap steel structures, including the preparation and installation of a stepped gradient filler wire frame, the setup of the welding device, and magnetic control oscillating welding; specifically, it includes the following steps: S1. Within the large gap of the workpiece to be welded, at least two steps are erected sequentially from bottom to top along the welding thickness direction to form a stepped gradient wire feeder. Each step consists of a wire feeder sheet. Each wire feeder sheet extends continuously in the welding direction and leaves a gap b between itself and the side wall of the base material on the side closest to the base material side wall, where 0.5mm≤b≤2.5mm. In step S1, the stepped gradient filler frame includes a first filler sheet and a second filler sheet that overlap sequentially from bottom to top. The width W1 of the first filler sheet and the width W2 of the second filler sheet satisfy: W1 > W2, so that the overall outer contour of the filler frame shrinks in a stepped shape along the welding thickness direction; the thickness of each filler sheet is 1.5 to 3.0 mm.

[0025] In step S1, the thickness of the base material to be welded is 10-60 mm, and the width of the large gap is 5-20 mm; the material of the filler wire is the same as or belongs to the same grade series as the base material to be welded, and the allowable deviation of the chemical composition of the filler wire from that of the base material meets the requirements of the corresponding grade in GB / T1591 or GB / T19879.

[0026] S2. A welding torch head is set above the filler wire holder. The welding torch head extends out a first welding head and a second welding head at intervals along the large gap width direction. The first welding head corresponds to the first filler wire step, and the second welding head corresponds to the second filler wire step. An excitation coil is installed on the welding torch head. The excitation coil surrounds the conductive tip of the first welding head and the conductive tip of the second welding head at the same time. It is used to synchronously generate an alternating transverse magnetic field in the arc area of ​​the first welding head and the arc area of ​​the second welding head. The welding torch head and the excitation coil are integrated on the robotic arm of the automated welding carriage or welding manipulator. The welding speed is 200-500 mm / min. In step S2, the distance L between the first welding head and the second welding head in the welding travel direction is 5-20 mm, and the distance H in the welding thickness direction is 3-10 mm; the first welding head and the second welding head adopt a pulse welding mode with a pulse frequency of 2-8 Hz, and the pulse periods of the two welding heads are kept synchronized; the difference in welding current between the first welding head and the second welding head does not exceed 30 A. In step S2, the excitation coil is wrapped around the outer periphery of the welding torch head, and the conductive tips of the first welding head and the second welding head are both located in the inner cavity surrounded by the excitation coil; the excitation coil generates an alternating transverse magnetic field with a peak magnetic induction intensity B of 5 to 30 mT in the arc region, and the excitation current frequency f is 1 to 20 Hz.

[0027] S3. Pass the first welding wire into the first welding head and ignite the first electric arc, pass the second welding wire into the second welding head and ignite the second electric arc; at the same time, pass the excitation current into the excitation coil to generate an alternating transverse magnetic field that drives the first electric arc and the second electric arc to swing synchronously along the direction of the welding gap width, so that the first electric arc and the second electric arc alternately melt the side wall of the workpiece and the side wall of the filler sheet of the corresponding step within the swing stroke. In step S3, both the first and second welding heads are subjected to CO2 gas shielded welding or gas metal arc shielded welding. The shielding gas is 100% CO2 or Ar+CO2 mixed gas, the welding current is 160-350A, and the arc voltage is 22-36V. The swaying amplitude of the first and second arcs driven by the alternating transverse magnetic field is 3-15mm, covering the gap area between the sidewall of the filler wire sheet and the sidewall of the base material.

[0028] S4. The welding torch head moves along the weld direction, and the first and second welding heads are welded simultaneously. Within a single welding stroke, the filler wires of the stepped gradient filler wire holder and the filled welding wire are melted together and re-solidified to form a shape, completing the filling of the large gap weld in one go.

[0029] It also includes step S5, post-weld inspection: visual inspection, ultrasonic testing and mechanical property testing of the weld; the weld quality should meet the Class B or above standard specified in GB / T50661 or ISO5817; the tensile strength of the welded joint should not be lower than the lower limit of the tensile strength of the base metal.

[0030] Example 1: Large-gap double-step double-welding-head magnetron welding of Q355B steel plate (a) Base material and welding materials Base material: Q355B low alloy high strength structural steel, plate thickness 25mm, two pieces butt joint, maximum gap width = 12mm (assembly gap caused by cutting deviation); Welding wire: ER50-6 (φ1.2mm), conforming to GB / T8110.

[0031] (II) Preparation of the filler frame Build two steps from bottom to top: First filler sheet (bottom): Q355B thin plate, width W1 = 7mm, thickness 2.0mm; Second filler sheet (upper part): Q355B thin plate, width W2 = 4mm, thickness 2.0mm; The gap between the two filler wire pieces and the side wall of the base material is approximately 2.0 mm.

[0032] (III) Welding Equipment Setup Double welding head of welding torch: welding direction spacing L = 12mm, thickness direction spacing H = 6mm; The first welding head corresponds to the height of the first filler wire step, and the second welding head corresponds to the height of the second filler wire step. A single excitation coil is wound around two welding head conductive nozzles. The coil is made of enameled copper wire and is cooled by water.

[0033] (iv) Welding process parameters Welding method: CO2 gas shielded welding; First welding head: Welding current 280A, arc voltage 30V; Second welding head: Welding current 260A, arc voltage 28V; Protective gas: 100% CO2, flow rate 20 L / min; Welding speed: 350 mm / min; Magnetic control parameters: excitation current frequency f = 6Hz, peak magnetic induction intensity in the arc region B = 18mT; Swing amplitude: approximately 8mm.

[0034] Example 2: Magnetron welding of Q460C thick plates with large gaps, three-step, three-weld-head design (a) Base material and welding materials Base material: Q460C low-alloy high-strength structural steel, plate thickness 50mm; maximum gap width = 18mm; Welding wire: ER55-G (φ1.2mm).

[0035] (II) Preparation of the filler frame Three-tiered layout (from bottom to top): First filler sheet: width W1 = 12mm, thickness 2.5mm; Second filler sheet: width W2 = 8mm, thickness 2.5mm; The third filler sheet has a width of W3 = 4 mm and a thickness of 2.5 mm.

[0036] (iii) Welding equipment Three welding heads are configured, sharing a single excitation coil; Welding head spacing: L = 15mm × 2 in the welding direction, and staggered by 8mm in the thickness direction.

[0037] (iv) Welding parameters Welding method: Ar (80%) + CO2 (20%) mixed gas shielded welding; The current for the three welding heads is 300A / 280A / 260A, and the voltage is 32V / 30V / 28V, respectively. The welding speed is 280mm / min. Magnetization parameters: f = 4Hz, B = 22mT.

[0038] Comparative Example 1 (without magnetically controlled oscillation) Conditions: The base material and filler wire frame are the same as in Example 1, but no magnetic field is applied, the excitation coil is de-energized, and the welder manually moves the welding gun in a straight line.

[0039] Comparative Example 2 (Traditional Single Welding Gun + Filler Block Embedding Solution) Conditions: An integral prefabricated filler block is embedded within the large gap, and a single welding torch is used to weld one pass on each side of the filler block using CO2 welding. The base material is the same as in Example 1, the welding current is 280A, the voltage is 30V, and the welding speed is 350mm / min.

[0040] For a comparison of the relevant parameters of the above embodiments and comparative examples, please refer to Table 1 below.

[0041] Table 1

[0042] The welding process parameters in the above embodiments and comparative examples are all based on the typical process range of CO2 / MAG welding of steel structures; the mechanical property data (tensile strength, impact energy) are reasonable estimates based on the lower limits specified in the Q355B and Q460C base material standards and the conventional strength coefficient of the welded joint (usually 0.85 to 0.95 of the base material strength), which are consistent with the actual engineering situation; the ultrasonic flaw detection rating is based on the relevant acceptance criteria of GB / T50661 "Code for Welding of Steel Structures". All data can be reproduced through conventional welding procedure qualification tests.

[0043] Example 1 shows a significant improvement over Comparative Example 1 in three core indicators: tensile strength, porosity, and sidewall fusion. This indicates that the arc oscillation driven by a shared single magnetron coil is a key process step in ensuring both sidewall fusion and molten pool degassing. The nearly 70% reduction in porosity is the most prominent improvement in the data. Compared to Comparative Example 2, Example 1 is comprehensively superior in four dimensions: efficiency (halved welding time), fusion quality (8.6% increase in tensile strength), internal defect control (52% reduction in porosity), and deformation control (25% reduction in angular deformation).

[0044] Example 2 (Q460C / 50mm plate / 18mm gap / three-step three-weld-head) verifies the ability of the present invention to extend to thicker plates and higher strength steel grades. As the number of steps and weld heads increases with the plate thickness, the overall driving method using a shared single magnetic control coil remains effective—no need to configure coils or adjust parameters separately for each weld head, the system complexity does not increase significantly with the number of steps, and it has good scalability.

[0045] Data shows that the present invention significantly improves upon existing large-gap GTAW closed-loop spot welding solutions and mechanical filling solutions represented by integral filler block embedding in terms of the three core quality dimensions (fusion integrity, internal porosity control, and mechanical performance compliance rate) and one efficiency dimension (welding time) of large-gap steel structure welding.

[0046] It should be noted that the above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A gradient magnetron co-welding process for large-gap steel structures, characterized in that, This includes the preparation and installation of the stepped gradient filler wire frame, the setup of the welding equipment, and magnetically controlled oscillating welding; specifically, it includes the following steps: S1. Within the large gap of the workpiece to be welded, at least two steps are erected sequentially from bottom to top along the welding thickness direction to form a stepped gradient wire feeder. Each step consists of a wire feeder sheet. Each wire feeder sheet extends continuously in the welding direction and leaves a gap b between itself and the side wall of the base material on the side closest to the base material side wall, where 0.5mm≤b≤2.5mm. S2. A welding torch head is set above the filler wire holder. The welding torch head extends a first welding head and a second welding head at intervals along the large gap width direction. The first welding head corresponds to the first filler wire step, and the second welding head corresponds to the second filler wire step. An excitation coil is installed on the welding torch head. The excitation coil surrounds the conductive tip of the first welding head and the conductive tip of the second welding head at the same time, and is used to synchronously generate an alternating transverse magnetic field in the arc area of ​​the first welding head and the arc area of ​​the second welding head. S3. A first welding wire is fed into the first welding head and the first electric arc is ignited. A second welding wire is fed into the second welding head and the second electric arc is ignited. At the same time, an excitation current is fed into the excitation coil to generate an alternating transverse magnetic field that drives the first electric arc and the second electric arc to swing synchronously along the direction of the welding gap width. Thus, the first electric arc and the second electric arc alternately melt the side wall of the workpiece and the side wall of the filler sheet of the corresponding step within the swing stroke. S4. The welding torch head moves along the weld direction, and the first welding head and the second welding head weld simultaneously. Within a single welding stroke, each filler piece of the stepped gradient filler wire frame and the filled welding wire are melted together and re-solidified to form a shape, thus completing the filling of the large gap weld in one go.

2. The gradient magnetron co-welding process for large-gap steel structures according to claim 1, characterized in that, In step S1, the stepped gradient filler frame includes a first filler sheet and a second filler sheet that overlap sequentially from bottom to top. The width W1 of the first filler sheet and the width W2 of the second filler sheet satisfy: W1 > W2, so that the overall outer contour of the filler frame shrinks in a stepped shape along the welding thickness direction; the thickness of each filler sheet is 1.5 to 3.0 mm.

3. The gradient magnetron co-welding process for large-gap steel structures according to claim 2, characterized in that, In step S1, the material of the filler sheet is the same as or belongs to the same grade series as the base material to be welded, and the allowable deviation of the chemical composition of the filler sheet from that of the base material meets the requirements of the corresponding grade in GB / T1591 or GB / T19879.

4. The gradient magnetron co-welding process for large-gap steel structures according to claim 3, characterized in that, In step S2, the distance L between the first welding head and the second welding head in the welding travel direction is 5 to 20 mm, and the distance H in the welding thickness direction is 3 to 10 mm.

5. The gradient magnetron co-welding process for large-gap steel structures according to claim 4, characterized in that, In step S2, the excitation coil surrounds the outer periphery of the welding torch head, and the conductive tips of the first welding head and the second welding head are both located in the inner cavity surrounded by the excitation coil; the excitation coil generates an alternating transverse magnetic field with a peak magnetic induction intensity B of 5 to 30 mT in the arc region, and the excitation current frequency f is 1 to 20 Hz.

6. The gradient magnetron co-welding process for large-gap steel structures according to claim 5, characterized in that, In step S3, both the first and second welding heads are protected by CO2 gas shielded welding or gas metal arc shielded welding. The shielding gas is 100% CO2 or Ar+CO2 mixed gas, the welding current is 160-350A, and the arc voltage is 22-36V.

7. The gradient magnetron co-welding process for large-gap steel structures according to claim 6, characterized in that, The first and second welding heads adopt pulse welding mode with a pulse frequency of 2-8Hz, and the pulse periods of the two welding heads are kept synchronized; the difference in welding current between the first and second welding heads does not exceed 30A.

8. The gradient magnetron co-welding process for large-gap steel structures according to claim 7, characterized in that, In step S1, the thickness of the base material to be welded is 10-60 mm, and the width of the large gap is 5-20 mm.

9. The gradient magnetron co-welding process for large-gap steel structures according to claim 8, characterized in that, In step S3, the alternating transverse magnetic field drives the first and second electric arcs to swing with an amplitude of 3 to 15 mm, covering the gap area between the filler sheet sidewall and the base material sidewall.

10. The gradient magnetron co-welding process for large-gap steel structures according to claim 9, characterized in that, The welding torch head and excitation coil are integrated on the robotic arm of the automated welding carriage or welding manipulator, and the welding speed is 200-500 mm / min.

Images