A welding method for reducing spatter of galvanized sheet

Abstract

The application provides a welding method for reducing gas hole splashing of galvanized sheet, and relates to the technical field of galvanized sheet welding. The welding method comprises a plurality of continuous welding periods, each of which comprises an alternating pulse welding stage and a pull wire short circuit welding stage. The pulse welding stage comprises a pulse period and an arc stabilizing period formed between the pulse period. In the pulse period, the welding wire is positively fed at a first constant speed, the welding current is raised to a first peak current, the first peak current is kept constant until the molten drop forms a necking structure, the welding current is raised to a molten drop thrust current, the arc thrust pushes away the molten pool, the root of the weld is exposed, and zinc vapor is evaporated to remove the zinc layer on the surface of the galvanized sheet. In the arc stabilizing period, the welding wire is positively fed at the first constant speed, the welding current is reduced from the molten drop thrust current to a first base current, the welding voltage is reduced, and the arc is stabilized.

Description

Technical Field

[0001] This invention relates to the field of galvanized sheet welding technology, and more specifically, to a welding method for reducing spatter from galvanized sheets. Background Technology

[0002] Galvanized steel sheets are widely used in automobile manufacturing, industrial production, and building construction due to their excellent corrosion resistance and relatively low price. However, arc welding, the main method for forming and joining galvanized steel sheets, presents a series of challenges. Since galvanized steel sheets are processed from carbon steel sheets through electroplating or zinc diffusion, the zinc layer inevitably burns off during welding. Zinc has a melting point of approximately 400°C to 900°C, while steel has a melting point of 1300°C to 1500°C, a significant difference. Zinc melts and evaporates preferentially. When steel reaches its melting point, zinc has already reached its boiling point and undergoes vigorous sublimation, producing a large amount of zinc vapor. This sublimated zinc vapor not only affects the transfer of molten droplets, causing excessive spatter, but also, if the zinc vapor does not escape in time, it creates numerous pores on the weld surface and inside, thus reducing weld quality. Summary of the Invention

[0003] The present invention aims to solve the problem that zinc vapor generated by the melting and evaporation of zinc layer during the welding of galvanized sheets can easily lead to porosity and spatter.

[0004] To address the aforementioned problems, this invention provides a welding method for reducing porosity and spatter in galvanized steel sheets. This method is applied to a consumable electrode welding method and includes multiple consecutive welding cycles. Each welding cycle includes an alternating pulse welding phase and a wire-pulling short-circuit welding phase. The pulse welding phase includes a pulse period and an arc stabilization period formed between the pulse periods. During the pulse period, the welding wire is fed forward at a first constant speed, the welding current increases to the first peak current, and the first peak current is maintained constant until the molten droplet forms a necking structure. The welding current increases to the molten droplet thrust current and the arc thrust pushes open the molten pool, exposing the root of the weld bead. Zinc vapor evaporates to remove the zinc layer on the surface of the galvanized sheet; wherein, the first constant speed is >0. During the arc stabilization period, the welding wire is fed forward at a first constant speed, and the welding current is reduced from the droplet thrust current to the first base value current, thereby reducing the welding voltage and maintaining arc stability. During the wire drawing and short-circuit welding stage, the arc length is reduced and the galvanized sheet is welded, the weld bead is filled, and zinc layer evaporation is reduced to decrease spatter and avoid magnetic blow.

[0005] Optionally, the wire drawing short-circuit welding stage includes During the forward feeding phase of the welding wire, the welding wire is fed forward at a second constant speed, and the first current and first voltage are output at a constant speed to ensure normal preheating of the welding wire; wherein, the first constant speed > the second constant speed > 0, and the first peak current > the first current; During the short-circuit contact period, after the welding wire contacts the galvanized plate, it enters a short-circuit state. The welding wire is fed forward at a third constant speed, the welding current increases to the second peak current, and the welding voltage drops to the second voltage to ensure short-circuit stability and allow the welding wire to melt and form droplets. Among these conditions, the second constant speed > the third constant speed > 0, the first peak current ≥ the second peak current > the first current, and the first voltage > the second voltage. During the droplet shrinkage period, the welding wire is fed forward at a constant third speed, the droplet shrinks steadily, and the droplet fully transitions into the molten pool. The welding current is steadily reduced, the second voltage is maintained, and the short-circuit state is maintained. During the wire retraction period, the wire is retracted at a fourth constant speed to separate the wire from the molten pool and prevent wire sticking. The welding current drops to the second current, the welding voltage rises to the third voltage, the arc is re-ignited, the arc is stabilized, and the weld bead is filled. Among these conditions, the fourth constant speed is less than 0, the absolute value of the second constant speed is greater than the absolute value of the fourth constant speed, the absolute value of the third constant speed is greater than the absolute value of the third constant speed, the first current is greater than the second current, and the third voltage is greater than or equal to the first voltage.

[0006] Optionally, the duration of the forward feed period of the welding wire is 0.1ms to 0.2ms, the duration of the short-circuit contact period is 0.05ms to 0.15ms, the duration of the droplet shrinkage period is 0.05ms to 0.15ms, and the duration of the wire retraction period is 0.02ms to 0.08ms.

[0007] Optionally, during the forward wire feed period, the second constant speed is 3 mm / s to 4 mm / s, the first current is 90 A to 110 A, and the first voltage is 17 V to 19 V.

[0008] Optionally, during the short-circuit contact period, the third constant velocity is 0.5 mm / s to 1 mm / s, the second peak current is 150 A to 200 A, and the second voltage is 6 V to 8 V.

[0009] Optionally, during the wire retraction period, the fourth constant speed is -2.5 mm / s to -3.5 mm / s, the second current is 80 A to 100 A, and the third voltage is 18 V to 20 V.

[0010] Optionally, during the pulse period, the first constant velocity is 3.5 mm / s to 4.5 mm / s, the first peak current is 150 A to 180 A, and the droplet thrust current is 190 A to 210 A.

[0011] Optionally, during the pulse period, the welding voltage corresponding to the welding current being the first peak current is 19 V to 21 V, and the welding voltage corresponding to the welding current being the droplet thrust current is 22 V to 24 V.

[0012] Optionally, during the arc stabilization period, the first base current is 70 A to 90 A, and the welding voltage is reduced to 16 V to 18 V.

[0013] Optionally, the time ratio of the pulse welding stage to the wire-drawing short-circuit welding stage is 1:1 to 3:2.

[0014] The beneficial effects of the welding method for reducing porosity and spatter in galvanized steel sheets according to the present invention are as follows: During the pulse phase, the wire is fed at a constant first constant speed to ensure uniform droplet formation and avoid arc vibration caused by unstable wire feeding. The first peak current is maintained constant until the droplet forms a necking structure. The welding current is increased to the droplet thrust current, providing continuous thrust, pushing open the molten pool to expose the weld root, opening the zinc vapor escape channel, ensuring timely discharge of zinc vapor, and reducing porosity. During the arc stabilization phase, the wire is fed at a constant first speed to ensure continuous wire replenishment. The welding current is reduced to the first base value current, which can reduce heat input, avoid excessive burning of the base material and zinc layer, and save energy. The welding voltage is reduced to cope with the interference of zinc vapor on the arc, avoid high voltage causing arc instability and magnetic blow, improve arc stiffness, ensure smooth connection of subsequent short-circuit welding, and further reduce undercut and magnetic blow defects. The welding current and welding voltage are maintained constant to maintain arc stability and avoid arc extinction or violent fluctuations. After the pulse welding stage, the zinc layer is effectively removed, and zinc vapor is smoothly discharged. The process then proceeds to the wire-drawing short-circuit welding stage, achieving low heat input to fill the weld bead and reducing spatter and porosity. This allows for high-speed welding of galvanized sheets with thicknesses from 1.5 mm to 3 mm, significantly improving welding efficiency. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the welding current waveform during one welding cycle of the welding method for reducing spatter in galvanized steel sheets according to an embodiment of the present invention. Figure 2 This is a waveform diagram of the wire feed rate, welding current, and welding voltage during a pulse welding stage according to an embodiment of the present invention. Figure 3 This is a schematic diagram of the weld seam after welding the galvanized sheet in Example 1; Figure 4 This is a schematic diagram of the weld seam after welding the galvanized sheet in Comparative Example 1. Detailed Implementation

[0016] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the accompanying drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0017] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this invention's description is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "comprising" and its variations as used herein are open-ended, meaning "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; and the term "optionally" means "optional embodiments". Definitions of other terms will be given in the following description. It should be noted that the concepts of "first" and "second" mentioned in this invention are used to distinguish different objects, not to describe a specific order or hierarchy. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature.

[0018] In related technologies, under short-circuit welding conditions in Metal Active Gas Arc Welding (MAG), it is crucial to avoid both excessive heat input leading to severe zinc layer burn-off and insufficient heat input preventing timely escape of zinc vapor from the weld. This balance is typically achieved by modifying the welding waveform and process. Generally, this involves reducing the peak current and peak time during the arc-ignition phase of the short-circuit process and increasing the inflection point current and rise slope during the short-circuit phase. However, these methods have limitations. For example, a thicker zinc layer increases the rate and concentration of zinc vapor volatilization. As welding progresses, the heat input to the substrate continuously increases, causing the volatilized zinc vapor to accumulate. If the working conditions are complex and zinc vapor cannot escape, it strongly inhibits droplet transfer, forcing the transfer to rely on gravity as the droplets grow. Furthermore, arc vibration at this point can lead to large spatter particles adhering to the workpiece, requiring grinding and affecting weld consistency.

[0019] To address the problems existing in the aforementioned related technologies, embodiments of the present invention provide a welding method for reducing spatter from galvanized steel sheets.

[0020] like Figure 1 As shown, an embodiment of the present invention provides a welding method for reducing porosity and spatter in galvanized steel sheets. This method is applied to a consumable electrode welding method and includes multiple consecutive welding cycles. Each welding cycle includes alternating pulse welding and wire-pulling short-circuit welding stages, such as... Figure 2 As shown, the pulse welding stage includes the pulse period and the arc stabilization period formed between the pulse periods; During the pulse phase, the welding wire is fed forward at a first constant speed, the welding current increases to the first peak current, and is maintained constant until the molten droplet forms a necking structure. The welding current then increases to the point where the droplet thrust current reaches the arc thrust, pushing open the molten pool and exposing the weld root. Zinc vapor evaporates, removing the zinc layer from the galvanized sheet surface. The first constant speed is greater than zero. Because the necking formation lasts extremely short, typically on the order of milliseconds or even sub-milliseconds (far shorter than the oscilloscope's time base setting), and the current rises and falls rapidly (with a large slope) before and after this phase, it is compressed into a single "peak" on the waveform display. The horizontal sustaining segment is submerged in the transition edge. Therefore... Figure 1 and Figure 2 The current waveforms did not show the pattern of "the welding current rising to the first peak current and maintaining the first peak current constant until the molten droplet forms a necking structure".

[0021] During the arc stabilization period, the welding wire is fed forward at a first constant speed, and the welding current is reduced from the droplet thrust current to the first base value current, thereby reducing the welding voltage and maintaining arc stability. During the wire drawing and short-circuit welding stage, the arc length is reduced and the galvanized sheet is welded, the weld bead is filled, and zinc layer evaporation is reduced to decrease spatter and avoid magnetic blow.

[0022] Specifically, Figure 2 When the welding current rises to the point where the droplet thrust current reaches the point where the arc thrust pushes the molten pool apart, the arc will be re-established instantly. At this time, the welding voltage will rise rapidly to a peak, forming a short-circuit peak voltage.

[0023] The first constant speed refers to the uniform wire feeding speed during the forward feed period. It can be achieved by servo motor control. Its function is to ensure that the wire feeds at a uniform speed without fluctuation, ensuring that the wire continues to melt and maintains a stable relative position with the galvanized base material, ensuring uniform formation of molten droplets, and avoiding arc vibration caused by unstable wire feeding. The first constant speed > 0 means that the forward feed direction of the wire is defined as the positive direction.

[0024] The welding current is increased to the droplet thrust current and maintained for a reference time of 0.2 ms to provide continuous arc thrust to push the molten pool apart.

[0025] In this embodiment, during the pulse phase, the wire is fed at a constant first constant speed to ensure uniform droplet formation and avoid arc jitter caused by unstable wire feeding. The first peak current is maintained constant until the droplet forms a necking structure. The welding current is increased to the droplet thrust current, providing continuous thrust to push open the molten pool, exposing the weld root and opening the zinc vapor escape channel to ensure timely zinc vapor discharge and reduce porosity. During the arc stabilization phase, the wire is fed at the first constant speed to ensure continuous wire replenishment. The welding current is reduced to the first base value current, which reduces heat input, avoids excessive burning of the base material and zinc layer, and saves energy. The welding voltage is reduced to cope with the interference of zinc vapor on the arc, avoids arc instability and magnetic blow caused by excessive voltage, improves arc stiffness, ensures smooth connection of subsequent short-circuit welding, and further reduces undercut and magnetic blow defects. The welding current and welding voltage are maintained constant to maintain arc stability and avoid arc extinction or violent fluctuations. After the pulse welding stage, the zinc layer is effectively removed, and zinc vapor is smoothly discharged. The process then proceeds to the wire-drawing short-circuit welding stage, achieving low heat input to fill the weld bead and reducing spatter and porosity. This allows for high-speed welding of galvanized sheets with thicknesses from 1.5 mm to 3 mm, significantly improving welding efficiency.

[0026] Optionally, the wire drawing short-circuit welding stage includes During the forward feeding phase of the welding wire, the welding wire is fed forward at a second constant speed, and the first current and first voltage are output at a constant speed to ensure normal preheating of the welding wire; wherein, the first constant speed > the second constant speed > 0, and the first peak current > the first current; During the short-circuit contact period, after the welding wire contacts the galvanized plate, it enters a short-circuit state. The welding wire is fed forward at a third constant speed, the welding current increases to the second peak current, and the welding voltage drops to the second voltage to ensure short-circuit stability and allow the welding wire to melt and form droplets. Among these conditions, the second constant speed > the third constant speed > 0, the first peak current ≥ the second peak current > the first current, and the first voltage > the second voltage. During the droplet shrinkage period, the welding wire is fed forward at a constant third speed, the droplet shrinks steadily, and the droplet fully transitions into the molten pool. The welding current is steadily reduced, the second voltage is maintained, and the short-circuit state is maintained. During the wire retraction period, the wire is retracted at a fourth constant speed to separate the wire from the molten pool and prevent wire sticking. The welding current drops to the second current, the welding voltage rises to the third voltage, the arc is re-ignited, the arc is stabilized, and the weld bead is filled. Among these conditions, the fourth constant speed is less than 0, the absolute value of the second constant speed is greater than the absolute value of the fourth constant speed, the absolute value of the third constant speed is greater than the absolute value of the third constant speed, the first current is greater than the second current, and the third voltage is greater than or equal to the first voltage.

[0027] Specifically, the second constant speed refers to the uniform wire feeding speed during the forward feed period, which can be achieved by servo motor control. Its function is to ensure that the wire feeds at a uniform speed without fluctuation, so as to ensure that the wire efficiently approaches and contacts the base material, thus preparing for short-circuit welding. The second constant speed > 0 means that the forward feed direction of the wire is defined as the positive direction.

[0028] The third constant speed refers to the uniform wire feeding speed during the forward feed period, which can be achieved by servo motor control. Its function is to feed at a uniform speed. The third constant speed is less than the second constant speed. During the short-circuit contact period, it can reduce the impact force of short-circuit contact, avoid excessive short-circuit pressure leading to molten pool disturbance and zinc vapor encapsulation, and reduce porosity. During the droplet shrinkage period, maintaining a low-speed feed can ensure that the droplets fully transition to the molten pool, avoid droplet accumulation, and ensure stable droplet shrinkage. The third constant speed > 0 means that the forward feed direction of the welding wire is specified as the positive direction.

[0029] The fourth constant speed refers to the speed at which the welding wire is pulled away in the reverse direction during the wire retraction period. This can be achieved by controlling the motor to reverse. Its function is to retract at a uniform speed, ensuring that the welding wire is controllably separated from the molten pool, re-igniting the arc, and preparing for the next welding cycle. Wire retraction can prevent wire sticking. The fourth constant speed < 0 means that the reverse direction of the welding wire is specified as the negative direction.

[0030] In this optional embodiment, during the forward feed phase, the welding wire is fed in the forward direction to ensure that it approaches and contacts the base material, preparing for short-circuit welding. The welding current changes by maintaining a constant output of the first current and first voltage without fluctuations, preheating the welding wire, and avoiding sudden current changes and spatter caused by cold contact. Simultaneously, the first current is lower than the first peak current to prevent excessive current from causing a large amount of zinc layer evaporation again. The stable voltage maintains arc stability, paving the way for subsequent short-circuit transition. During the short-circuit contact phase, after the welding wire contacts the base material, it enters a short-circuit state. The welding wire feed speed is reduced to decrease the impact force of the short-circuit contact, preventing excessive short-circuit pressure that could cause molten pool disturbance, zinc vapor encapsulation, and reduced porosity. The welding current increases to the second peak current to provide sufficient heat to melt the welding wire and form droplets. The welding voltage drops to the second voltage. In the short-circuit state, high voltage is not required to maintain the arc; the low voltage ensures short-circuit stability, avoids spatter caused by an unextinguished arc, and reduces arc burn-off of the zinc layer. During the droplet contraction phase, the droplet forms a contracted structure. Maintaining a low-speed feed at the third constant speed ensures a full transition of the droplet to the molten pool, preventing droplet accumulation. A stable reduction in welding current increases arc stiffness, preventing further burning of the galvanized layer and the formation of zinc vapor. It also avoids droplet breakage and spatter caused by sudden current changes, ensuring a smooth droplet transition and reducing weld porosity. During the wire retraction phase, the wire is retracted at the fourth constant speed. This retraction prevents wire sticking, ensuring controllable separation of the wire from the molten pool and re-ignition of the arc, preparing for the next welding cycle. The welding current is reduced to a slightly lower second current to avoid spatter caused by excessive current during separation, while ensuring successful arc ignition. The welding voltage is increased to the third voltage. After wire retraction, the arc reforms, requiring a voltage matching the voltage needed for a stable arc. After the wire-drawing short-circuit welding cycle is completed, the weld bead filling is finished, with no obvious spatter or porosity, and then the next welding cycle (i.e., the pulse welding stage and the wire-drawing short-circuit welding stage) is entered, realizing high-speed and high-quality welding of galvanized sheets. "Zinc removal + low heat input welding" effectively solves the pain points of galvanized sheet welding such as porosity, spatter, and magnetic blow.

[0031] Optionally, the duration of the forward feed period of the welding wire is 0.1ms to 0.2ms, the duration of the short-circuit contact period is 0.05ms to 0.15ms, the duration of the droplet shrinkage period is 0.05ms to 0.15ms, and the duration of the wire retraction period is 0.02ms to 0.08ms.

[0032] In this optional embodiment, the wire forward feed period lasts from 0.1 ms to 0.2 ms to maintain arc stability and pave the way for subsequent short-circuit transition; the short-circuit contact period lasts from 0.05 ms to 0.15 ms to provide sufficient heat to melt the wire and form droplets; the droplet contraction period lasts from 0.05 ms to 0.15 ms to allow the droplets to form a contracted structure and fully transition to the molten pool, avoiding droplet accumulation, increasing arc stiffness, preventing further burning of the galvanized layer and formation of zinc vapor, and avoiding droplet breakage and spatter caused by sudden current changes, ensuring a smooth droplet transition and reducing weld porosity; the wire retraction period lasts from 0.02 ms to 0.08 ms to ensure controllable separation of the wire from the molten pool and re-ignition of the arc, paving the way for the next welding cycle; after the wire retraction short-circuit welding cycle ends, the weld bead is filled, with no obvious spatter or porosity.

[0033] Optionally, during the forward wire feed period, the second constant speed is 3 mm / s to 4 mm / s, the first current is 90 A to 110 A, and the first voltage is 17 V to 19 V.

[0034] In this optional embodiment, a second constant speed of 3 mm / s to 4 mm / s allows the welding wire to quickly approach and contact the base material, preparing for short-circuit welding while avoiding excessive speed that could cause the welding wire to bend or become unstable. A first current of 90 A to 110 A can preheat the welding wire, avoiding sudden current changes and spatter caused by cold contact, while also preventing excessive current from causing the zinc layer to evaporate again. A stable voltage maintains arc stability, paving the way for subsequent short-circuit transition.

[0035] Optionally, during the short-circuit contact period, the third constant velocity is 0.5 mm / s to 1 mm / s, the second peak current is 150 A to 200 A, and the second voltage is 6 V to 8 V.

[0036] In this optional embodiment, the wire feed speed is reduced to avoid excessive short-circuit pressure causing disturbance of the molten pool and zinc vapor encapsulation, thus reducing porosity; the current rises rapidly with a linear upward trend to provide sufficient heat to melt the welding wire and form droplets, while controlling it between 150 A and 200 A to avoid excessive current causing excessive evaporation of the zinc layer and increased spatter; the voltage drops in a stepwise manner to 6-8V because high voltage is not required to maintain the arc under short-circuit conditions, and low voltage can ensure short-circuit stability, avoid spatter caused by unextinguished arc, and reduce arc burn-off of the zinc layer.

[0037] In some specific embodiments, during the droplet shrinkage period, the droplet forms a shrinkage structure, and a low-speed feed is maintained to ensure that the droplet fully transitions to the molten pool and avoids droplet accumulation; the current is gradually reduced to increase the arc stiffness and prevent the arc from further burning the zinc layer and forming zinc vapor. At the same time, it avoids droplet breakage and splashing caused by sudden current changes, ensuring a smooth droplet transition and reducing weld porosity.

[0038] Optionally, during the wire retraction period, the fourth constant speed is -2.5 mm / s to -3.5 mm / s, the second current is 80 A to 100 A, and the third voltage is 18 V to 20 V.

[0039] In this optional embodiment, the retraction speed is controlled between -2.5 mm / s and -3.5 mm / s to avoid excessively fast retraction causing violent arc fluctuations and spatter, or excessively slow retraction causing wire sticking; a slightly low current of 80 A to 100 A is maintained to avoid excessive current during separation causing spatter, while ensuring smooth arc ignition; the voltage rises synchronously because the arc reforms after the welding wire is retracted, and the voltage required to stabilize the arc needs to be matched. At the same time, the voltage range is controlled to avoid excessively high voltage causing excessive arc length and magnetic blow, further reducing spatter and porosity.

[0040] Optionally, during the pulse period, the first constant velocity is 3.5 mm / s to 4.5 mm / s, the first peak current is 150 A to 180 A, and the droplet thrust current is 190 A to 210 A.

[0041] Specifically, the first peak current is 150 A to 180 A, which is about 50% of the normal pulse peak current. This avoids excessive current causing excessive burning of the zinc layer and a surge in zinc vapor, while ensuring that the welding wire melts normally to form droplets.

[0042] In this optional embodiment, a constant wire feed speed of 3.5 mm / s to 4.5 mm / s ensures that the welding wire continues to melt, resulting in uniform droplet formation and a stable relative position with the base material. The uniform feed speed avoids arc vibration caused by unstable wire feeding. The first peak current is 150 A to 180 A to avoid excessive current causing excessive zinc layer burn-off and zinc vapor surge, while ensuring normal melting of the welding wire to form droplets. The current is maintained constant until the droplets form a necking structure. After the droplets neck, the current is increased to the droplet thrust current to provide continuous arc separation thrust, pushing open the molten pool to expose the root of the weld bead, opening the zinc vapor escape channel, ensuring timely discharge of zinc vapor, and reducing porosity.

[0043] In some specific embodiments, the droplet thrust current is maintained for more than 0.2 ms to provide continuous arc separation thrust.

[0044] Optionally, during the pulse period, the welding voltage corresponding to the welding current being the first peak current is 19 V to 21 V, and the welding voltage corresponding to the welding current being the droplet thrust current is 22 V to 24 V.

[0045] In this optional embodiment, the voltage and current are synchronized to maintain arc stability without drastic fluctuations, avoid arc deflection caused by voltage abnormalities, and further reduce spatter.

[0046] Optionally, during the arc stabilization period, the first base current is 70 A to 90 A, and the welding voltage is reduced to 16 V to 18 V.

[0047] Specifically, the welding voltage can be controlled by the secondary switch of the insulated gate bipolar transistor (IGBT) in the metal inert gas welding (MIG) welding machine to stabilize the voltage within a preset range and reduce fluctuations.

[0048] In this optional embodiment, after the pulse period ends, the zinc layer has been initially removed, and it is necessary to maintain arc stability to avoid arc extinction or violent fluctuations. During the arc stabilization period, the current is reduced to the first base current of 70 A to 90 A to reduce heat input, avoid excessive burning of the base material and zinc layer, and save energy. The welding voltage is reduced to 16 V to 18 V to avoid arc instability and magnetic blow caused by excessive voltage, improve arc stiffness, ensure smooth connection of subsequent short-circuit welding, and further reduce undercut and magnetic blow defects.

[0049] Optionally, the time ratio of the pulse welding stage to the wire-drawing short-circuit welding stage is 1:1 to 3:2.

[0050] Specifically, the total duration of the pulse welding cycle is approximately 0.5 ms. After the pulse welding cycle ends, the zinc layer is effectively removed and the zinc vapor is smoothly discharged. Then, the wire-pulling short-circuit welding cycle begins, which lasts approximately 0.4 ms. This cycle enables low heat input to fill the weld bead, reducing spatter and porosity.

[0051] In this optional embodiment, the selection of the duration ratio between the pulse welding stage and the wire-drawing short-circuit welding stage can effectively remove the zinc layer, smoothly discharge zinc vapor, and complete the low-heat-input filler weld, reducing spatter and porosity.

[0052] In some specific embodiments, the welding apparatus for reducing spatter from galvanized steel sheets includes a welding control circuit connected to the electrodes and a servo motor-controlled wire-drawing welding torch. The welding control circuit is used to provide welding current to the electrode in each welding cycle; the servo motor controls the wire-drawing welding torch to control the feed speed and feed direction of the welding wire; the electrode is used to apply current to the welding part through the welding wire; wherein, the servo motor controls the wire-drawing welding torch to be connected to the welding torch control circuit, which is used to control the welding torch to swing back and forth along the welding direction.

[0053] The distance for pulse cleaning of the galvanized layer during the welding process depends on the oscillation distance of the welding torch. Generally, the torch oscillation is within ±4mm, and the welding frequency is controlled below 4 Hz. For a welding speed of 0.8 m / min, the frequency is 4 Hz; for a welding speed of 0.6 m / min, the frequency is 3 Hz; and for a welding speed of 0.5 m / min, the frequency is 2.5 Hz. The specific frequency needs to be adjusted according to the actual oscillation amplitude; a larger oscillation amplitude requires a lower frequency.

[0054] The present invention will be further described below with reference to specific embodiments.

[0055] Example 1: Welding method for galvanized sheet using 1.2 mm diameter welding wire.

[0056] During the pulse phase, the welding wire is fed forward at a speed of 4 mm / s at a constant speed to ensure continuous melting of the welding wire and stability with the base material. The welding current is rapidly increased to 180A and the welding voltage is 20V, and maintained constant until the molten droplet forms a necking structure. After the molten droplet necks, the current is immediately increased to 200A and the welding voltage is 23V, and maintained for 0.2 ms to provide continuous arc separation thrust.

[0057] During the arc stabilization period, the welding wire is fed forward at a speed of 4 mm / s at a constant speed. The welding current rapidly decreases to 80 A, and the welding voltage decreases to 17 V. The total duration of the pulse period and the arc stabilization period is 0.5 ms.

[0058] During the wire forward feed period, the wire is fed forward at a speed of 3.5 mm / s, with uniform feed. The welding current is maintained at 100 A with constant output, and the welding voltage is 18 V. Ensure that the wire is properly preheated and maintain this position for 0.15 ms.

[0059] During the short-circuit contact period, the welding wire is fed forward at a speed of 1 mm / s. This uniform feeding reduces the impact force of the short-circuit contact. The welding current rises rapidly to 180 A, and the welding voltage drops rapidly to 7 V in a step-like manner, remaining constant for 0.1 ms.

[0060] During the droplet shrinkage period, the welding wire is fed forward at a speed of 1 mm / s at a constant speed. The welding current decreases gradually while the welding voltage remains constant for 0.1 ms.

[0061] During the wire retraction period, the wire is retracted in the opposite direction at a speed of -3 mm / s. The welding current drops to 90 A, and the welding voltage rises rapidly to 19 V in a step-like manner, remaining constant for 0.05 ms.

[0062] Repeat the above welding cycle multiple times.

[0063] The galvanized sheet obtained after welding is as follows Figure 3As shown, the weld surface is smooth with a regular fish-scale pattern, the transition between weld segments is smooth, and there are no pores, spatter, or magnetic blow, resulting in a significant improvement in overall consistency.

[0064] Comparative Example 1: The galvanized sheet was welded using conventional methods with gas metal arc welding (MAG); the resulting galvanized sheet was as follows: Figure 4 As shown, there are obvious spatter particles on the weld surface and the surrounding base material, and there are also defects such as porosity and slag inclusions on the weld.

[0065] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A welding method for reducing spatter from porosity in galvanized steel sheets, characterized in that, A welding method applied to consumable electrodes includes multiple consecutive welding cycles, each welding cycle including alternating pulse welding phases and wire-pulling short-circuit welding phases, the pulse welding phase including a pulse period and an arc stabilization period formed between the pulse periods; During the pulse period, the welding wire is fed forward at a first constant speed, the welding current is increased to a first peak current, the first peak current is maintained constant until the molten droplet forms a necking structure, the welding current is increased to the molten droplet thrust current to the arc thrust to push open the molten pool, so that the root of the weld bead is exposed, and zinc vapor evaporates to remove the zinc layer on the surface of the galvanized sheet; wherein, the first constant speed is >0. During the arc stabilization period, the welding wire is fed forward at the first constant speed, the welding current is reduced from the droplet thrust current to the first base value current, the welding voltage is reduced, and the arc is maintained. During the wire-drawing short-circuit welding stage, the arc length is reduced and the galvanized sheet is welded to fill the weld bead, thereby reducing zinc layer evaporation, reducing spatter, and avoiding magnetic blow. The wire drawing short-circuit welding stage includes: During the forward feeding phase of the welding wire, the welding wire is fed forward at a second constant speed, and a first current and a first voltage are output at a constant speed to ensure normal preheating of the welding wire; wherein, the first constant speed > the second constant speed > 0, and the first peak current > the first current; During the short-circuit contact period, after the welding wire contacts the galvanized plate, it enters a short-circuit state. The welding wire is fed forward at a third constant speed, the welding current increases to the second peak current, and the welding voltage drops to the second voltage to ensure short-circuit stability, causing the welding wire to melt and form droplets. Wherein, the second constant speed > the third constant speed > 0, the first peak current ≥ the second peak current > the first current, and the first voltage > the second voltage. During the droplet shrinkage period, the welding wire is fed forward at the third constant speed, the droplet shrinks steadily, the droplet fully transitions into the molten pool, the welding current is steadily reduced, the second voltage is maintained, and the short-circuit state is maintained. During the wire retraction period, the welding wire is retracted at a fourth constant speed to separate the welding wire from the molten pool, preventing wire sticking. The welding current drops to the second current, the welding voltage rises to the third voltage, the arc is reignited, the arc is stabilized, and the weld bead filling is completed. Wherein, the fourth constant speed is less than 0, the absolute value of the second constant speed is greater than the absolute value of the fourth constant speed, the absolute value of the third constant speed, the first current is greater than the second current, and the third voltage is ≥ the first voltage.

2. The welding method for reducing porosity and spatter in galvanized steel sheets according to claim 1, characterized in that, The duration of the forward feed period of the welding wire is 0.1ms to 0.2ms, the duration of the short-circuit contact period is 0.05ms to 0.15ms, the duration of the droplet shrinkage period is 0.05ms to 0.15ms, and the duration of the welding wire retraction period is 0.02ms to 0.08ms.

3. The welding method for reducing porosity and spatter in galvanized steel sheets according to claim 1, characterized in that, During the forward feed of the welding wire, the second constant speed is 3 mm / s to 4 mm / s, the first current is 90 A to 110 A, and the first voltage is 17 V to 19 V.

4. The welding method for reducing porosity and spatter in galvanized steel sheets according to claim 1, characterized in that, During the short-circuit contact period, the third constant velocity is 0.5 mm / s to 1 mm / s, the second peak current is 150 A to 200 A, and the second voltage is 6 V to 8 V.

5. The welding method for reducing porosity and spatter in galvanized steel sheets according to claim 1, characterized in that, During the wire retraction period, the fourth constant speed is -2.5 mm / s to -3.5 mm / s, the second current is 80 A to 100 A, and the third voltage is 18 V to 20 V.

6. The welding method for reducing porosity and spatter in galvanized steel sheets according to claim 1, characterized in that, During the pulse period, the first constant velocity is 3.5 mm / s to 4.5 mm / s, the first peak current is 150 A to 180 A, and the droplet thrust current is 190 A to 210 A.

7. The welding method for reducing porosity and spatter in galvanized steel sheets according to claim 1, characterized in that, During the pulse period, the welding voltage corresponding to the welding current being the first peak current is 19 V to 21 V, and the welding voltage corresponding to the welding current being the droplet thrust current is 22 V to 24 V.

8. The welding method for reducing porosity and spatter in galvanized steel sheets according to claim 1, characterized in that, During the arc stabilization period, the first base current is 70 A to 90 A, and the welding voltage is reduced to 16 V to 18 V.

9. The welding method for reducing porosity and spatter in galvanized steel sheets according to claim 1, characterized in that, The time ratio of the pulse welding stage to the wire drawing short-circuit welding stage is 1:1 to 3:2.

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