US-20260124694-A1 - METAL TRANSFER CONTROLLED PULSED WELDING PROCESS

US20260124694A1US 20260124694 A1US20260124694 A1US 20260124694A1US-20260124694-A1

Abstract

A method of controlling a pulsed welding process, in which an electrode tip of a consumable electrode is advanced toward a workpiece, comprises: generating a pulsed current waveform having repetitive cycles; supplying the pulsed current waveform to the electrode tip to strike an arc on the workpiece during each cycle, wherein a cycle of the repetitive cycles includes: a pulse forming period that includes a forming pulse to form a droplet at the electrode tip, wherein the forming pulse includes a first peak that has a first peak duration; and a pulse detachment period that includes a detachment pulse separated from the forming pulse and configured to transfer the droplet from the electrode tip to the workpiece, wherein the detachment pulse includes a second peak that has a second peak duration that is less than the first peak duration.

Inventors

Rastislav Kubicek
Karl Jakob Erik Lennartsson
Bo Daniel Lennartsson
Lars David Leif Juliusson

Assignees

THE ESAB GROUP, INC.

Dates

Publication Date: 20260507
Application Date: 20241107

Claims (20)

1 . A method of controlling a pulsed welding process in which an electrode tip of a consumable electrode is advanced toward a workpiece, comprising: generating a pulsed current waveform having repetitive cycles; and supplying the pulsed current waveform to the electrode tip to strike an arc on the workpiece during each cycle, wherein a cycle of the repetitive cycles includes: a forming period that includes a forming pulse to form a droplet at the electrode tip, wherein the forming pulse includes a first peak that has a first peak duration; and a detachment period that includes a detachment pulse separated from the forming pulse and configured to transfer the droplet from the electrode tip to the workpiece, wherein the detachment pulse includes a second peak that has a second peak duration that is less than the first peak duration.
2 . The method of claim 1 , wherein: the first peak has a first peak level and the second peak has a second peak level that is greater than the first peak level.
3 . The method of claim 1 , wherein the forming period further includes: a first inter-pulse segment between the forming pulse and the detachment pulse, wherein the first inter-pulse segment has a first inter-pulse level that is less than each of a first peak level of the forming pulse and a second peak level of the detachment pulse.
4 . The method of claim 3 , wherein: the first inter-pulse level is a background level.
5 . The method of claim 3 , wherein: the first inter-pulse level is greater than a background level.
6 . The method of claim 3 , wherein the detachment period includes: a second inter-pulse segment following the detachment pulse and that has a second inter-pulse level that is less than both the first peak level and the second peak level.
7 . The method of claim 6 , wherein: the first inter-pulse level and the second inter-pulse level differ from each other.
8 . The method of claim 3 , wherein: a next cycle following the cycle includes a next forming pulse that has a third peak; and a first peak-to-peak duration between the first peak and the second peak differs from a second peak-to-peak duration between the second peak and the third peak.
9 . The method of claim 1 , further comprising: controlling the forming pulse and the detachment pulse to deliver equal energy levels to the electrode tip in the cycle.
10 . The method of claim 1 , wherein: the first peak duration is greater than the second peak duration; and the first peak has a first peak level and the second peak has a second peak level that is greater than the first peak level.
11 . The method of claim 1 , wherein: the pulsed welding process is performed without intentionally shorting the electrode tip to the workpiece during each cycle.
12 . The method of claim 1 , wherein: the detachment pulse includes a first rising edge, the first peak, and a first falling edge during which the droplet detaches from the electrode tip.
13 . The method of claim 1 , wherein: the forming pulse includes a first rising edge, the first peak, and a first falling edge; and the detachment pulse includes a second rising edge, the second peak, and a second falling edge during which the droplet detaches from the electrode tip, wherein the first falling edge has a greater duration than each of the second rising edge and the second falling edge.
14 . A welding system comprising: a power supply; and a controller to control the power supply during a pulsed welding process by causing the power supply to supply, to an electrode tip of a consumable electrode configured to advance toward a workpiece, a pulsed current waveform having repetitive cycles to strike an arc on the workpiece during each cycle, wherein a cycle of the repetitive cycles includes: a forming period that includes a forming pulse to form a droplet at the electrode tip, wherein the forming pulse includes a first peak that has a first peak duration; and a detachment period that includes a detachment pulse separated from the forming pulse and configured to transfer the droplet from the electrode tip to the workpiece, wherein the detachment pulse includes a second peak that has a second peak duration that is less than the first peak duration.
15 . The welding system of claim 14 , wherein: the first peak has a first peak level and the second peak has a second peak level that is greater than the first peak level.
16 . The welding system of claim 14 , wherein the forming period further includes: a first inter-pulse segment between the forming pulse and the detachment pulse, wherein the first inter-pulse segment has a first inter-pulse level that is less than each of a first peak level of the forming pulse and a second peak level of the detachment pulse.
17 . The welding system of claim 16 , wherein: the first inter-pulse level is a background level.
18 . The welding system of claim 16 , wherein: the first inter-pulse level is greater than a background level.
19 . The welding system of claim 16 , wherein the detachment period includes: a second inter-pulse segment following the detachment pulse and that has a second inter-pulse level that is less than both the first peak level and the second peak level.
20 . The welding system of claim 19 , wherein: the first inter-pulse level and the second inter-pulse level differ from each other.

Description

TECHNICAL FIELD The present disclosure relates to a pulsed welding process. BACKGROUND Pulsed Gas Metal Arc Welding (GMAW) including pulsed Metal Inert Gas (MIG) welding and Metal Active Gas (MAG) (MIG/MAG) welding involves supplying power in the form of current and voltage to a consumable wire electrode to form an electric arc between a tip of the wire electrode (i.e., the “electrode tip”) and a workpiece on which melted welding material from the electrode tip is deposited, and which forms a weld when cooled. During the pulsed welding process, a welding power supply generates a pulsed current waveform and supplies the same to the electrode tip. Controlling melting characteristics of metal droplets at the electrode tip, and their transfer to the workpiece, to achieve consistent high-quality results across a wide range or welding conditions, presents a challenge. This is especially true given the indirect relationship between various parameters of the pulsed current waveform, droplet melt conditions, and the timing of droplet transfer. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an illustration of an example welding system in which embodiments directed to controlling melting characteristics of metal transfer in a pulsed welding process may be implemented. FIG. 2 is a block diagram of a power supply and a power supply controller (PSC) of the welding system, according to an example embodiment. FIG. 3 shows an example pulsed current waveform generated by the power supply for the pulsed welding process, and an example plot of droplet-size growth over time as a result of the pulsed current waveform. FIG. 4 shows another example pulsed current waveform for the pulsed welding process. FIG. 5 shows yet another example pulsed current waveform for the pulsed welding process. FIG. 6 is a flowchart of an example method of controlling melting characteristics of metal transfer in the pulsed welding process performed by the welding system. FIG. 7 is a flowchart of an example method of weld energy level control implemented over a cycle of the pulsed current waveform. FIG. 8 is a diagram of the PSC accordance to an embodiment. DETAILED DESCRIPTION Overview In an embodiment, a method of controlling a pulsed welding process, in which an electrode tip of a consumable electrode is advanced toward a workpiece, comprises: generating a pulsed current waveform having repetitive cycles; supplying the pulsed current waveform to the electrode tip to strike an arc on the workpiece during each cycle, wherein a cycle of the repetitive cycles includes: a pulse forming period that includes a forming pulse to form a droplet at the electrode tip, wherein the forming pulse includes a first peak that has a first peak duration; and a pulse detachment period that includes a detachment pulse separated from the forming pulse and configured to transfer the droplet from the electrode tip to the workpiece, wherein the detachment pulse includes a second peak that has a second peak duration that is less than the first peak duration. Example Embodiments With reference to FIG. 1, there is an illustration of an example metal inert gas (MIG)/metal active gas (MAG) welding system 100, in which controlling melting characteristics of metal transfer in a pulsed welding process may be implemented. The embodiments are presented in the context of MIG/MAG welding by way of example only. It is understood that the embodiments may be employed generally in any known or hereafter developed welding environments, such as, but not limited to, tungsten inert gas (TIG) welding, flux cored arc welding (FCAW), shielded metal arc welding (SMAW) or stick welding, submerged arc welding (SAW), and so on. Welding system 100 includes: a power supply 102; a power supply controller (PSC) 104 coupled to and configured to control the power supply; an electrode feeder 106 coupled to the power supply; a cable assembly 108 coupled to the electrode feeder; a welding torch 110 (also referred to as a “welding gun”) coupled to the cable assembly and having a sturdy metal contact tip 111 that extends from an end of the welding gun or torch; a gas container 112 coupled to the cable assembly; and a workpiece 114 coupled to the power supply through at least a return path/cable 115. In the ensuing description, the terms “weld” and “welding” are synonymous and interchangeable. Electrode feeder 106 includes an electrode feeder 116 to feed an electrode from a coiled electrode 120 through cable assembly 108 and through contact tip 111 of welding torch 110, which is in electrical contact with the electrode. Under control of PSC 104, power supply 102 generates weld power that drives the welding process. In welding processes that involve a pulsed or periodic waveform, the weld power typically includes a series of weld current pulses. Power supply 102 provides the weld power from an output terminal 130a of the power supply to the electrode, through electrode feeder 116, cable assembly 108, and welding torc