JPH0555231B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to spray mode gas metal arc welding using consumable wire electrodes, and more particularly to the application of a method for stably depositing metal in an axial spray mode. This invention relates to an improvement in a gas metal arc welding method that can expand the range of welding that can be performed.

BACKGROUND OF THE INVENTION Gas metal arc welding, commonly referred to as "GMAW" or "MIG", is an arc welding process in which the arc is shielded from the surrounding atmosphere by a "gas (inert gas)". "Metal" is transferred from the consumable wire electrode through the arc.
The consumable wire electrode is continuously fed into the arc at a preselected rate corresponding to a predetermined deposition rate for a given wire size. The mode of metal transfer depends on operating parameters such as welding current, welding voltage, wire size, wire speed, electrode extension distance, and protective gas shield composition. Known modes of metal migration include short circuit, globular migration, axial spray migration, pulsed spray migration, and rotary arc axial spray migration. Those skilled in the art should be familiar with these terms and their technical content. Metal migration in short-circuit, globular and pulsed spray regimes is generally around 101 b/hr (4.5
It is a low welding rate process where welding is performed at a low welding rate of less than 1 kg/hr). On the other hand, rotary arc axial spray style metal transfer is a very high deposition rate process, approximately 171 b/hr using electrode wire size diameters of 0.035 inch (0.89 mm) or larger.
Welding speeds lower than (7.65Kg/hr) are unstable. Below this minimum metal deposition rate, the rotating arc becomes erratic and/or fails to connect.
Axial spray mode metal transfer exceeds the low deposition rates afforded by short circuit, globular and pulsed spray mode metal transfer and lower than the very high deposition rates obtained in rotary arc axial spray mode metal transfer. It is used for welding.

PRIOR ART A notable recent development in the field of gas metal arc welding is the method described in U.S. Patent No. 4,645,903, which
251b/hr using wire diameter dimensions within the range
Enables stable welding in metal transfer in axial spray mode up to speeds of (11.25 Kg/hr). Prior to the advent of this patent, metal transfer in axial spray mode was 5 to 121 b/hr (2.3 to 5.4 Kg/hr) using the aforementioned wire dimensions.
metal welding speed limited to If this maximum welding speed is exceeded, the welding operation will become turbulent and less stable, and eventually the rotating arc will increase the wire feed speed to the minimum required welding speed for a stable rotating arc. It will have to be established.

Employing metal transfer in a non-rotating arc axial spray mode is generally the preferred metal transfer mode choice for all position GMAW welding requiring reliability, stability, high quality and at least relatively high deposition rates. It is believed that there is. In the axial spray mode of metal transfer, fine droplets of molten metal are pinched off the end of the moving wire and transferred through the arc column into the weld pool. The pinch effect is caused by electromagnetic force on the molten tip of the wire. In the past, a rotating spray arc was generated to increase the working weld area for GMAW welding. In rotating arc mode metal transfer, the arc is physically rotated in a helical pattern about a longitudinal axis by electromagnetic forces. As the arc rotates, a controlled stream of metal droplets is transferred from the electrode tip to the weld pool over a relatively wide area.

However, the weld penetration provided by the non-rotating arc axial spray transfer mode is much deeper and easier to control than that provided by the rotating arc mode.

SUMMARY OF THE INVENTION There is thus a need to develop an improved spray mode gas metal arc welding process that is capable of increasing metal coverage for metal welding in an axial spray mode.

It is an object of the present invention to provide an improved spray mode gas metal arc welding method which makes it possible to significantly increase the welding rate, making it possible to deposit metal stably in an axial spray mode. .

Means for Solving the Problems The present inventors have determined that the combination of shielding gas mixture composition and specific operating parameter conditions holds one of the important keys to solving the above problems. It came to this.

Based on this knowledge, the present invention provides 0.023 to 0.052
A method for axial spray mode gas metal arc welding using a consumable wire electrode having a diameter within the range of 0.58 to 1.3 mm, the method comprising: (a) connecting the consumable wire electrode to a workpiece; (b) maintaining a substantially constant arc voltage in the range of 24 to 51 V between the wire electrode and the workpiece; and (c) the consumable wire electrode. into the arc through a welding torch contact tube, where the welding torch contact tube has a diameter of 0.5 to 1.5 inches (12.7 to 38.1 mm).
A welding torch with a torch cap that maintains a distance away from the workpiece and extends the welding torch contact tube beyond the tip of the contact tube by at least 5/32 inch (3.97 mm) to allow for electrode extension of at least 5/32 inch (3.97 mm) (d) transferring metal from said wire electrode to a workpiece;
(e) converting said arc to (A) 3-8% by volume carbon dioxide, (B) 30-40% by volume argon, and ( C) shielding with a gas mixture consisting of a balance of helium.

Description of examples The present invention will be explained in detail with reference to the drawings.

Referring to FIG. 1, the consumable wire electrode 1 is
It is unwound from the reel 12 by a feed roll 14 and drawn through a contact tube 16 in the gas-shielded arc welding torch 2 . The consumable wire electrode is
It has a diameter within the range of 0.023 to 0.052 inches (0.58 to 1.32 mm) and can be constructed of any suitable metal composition suitable for the particular welding application. Examples of suitable metals include any wire such as ER70S-3, -6, -7 gas metal arc welding wire listed in American Welding Society Specification A5.18.

Any suitable gas shielded torch may be used to carry out the method of the invention. One suitable example of such a torch is the ST-16 torch available from Eltech Corporation. The torch may be operated manually or automatically. In the embodiment illustrated in FIG. 1, torch 2 is an automated torch. The feed roll 14 is driven by a drive motor 3 housed in a wire feed unit 18. The motor 3 is capable of feeding the wire at the speed necessary to achieve the desired welding speed. One commercially available feed unit is the "High Deposition" feeder manufactured by Eltec Corporation, which can feed wire at speeds up to 2000 inches per minute (5080 cm).

To assist in handling the inertia of the rotating wire package, a sliding brake with an adaptive burnback circuit may be used to prevent the wire from welding to the contact tube at the end of the welding operation. preferable.

A power supply 20 provides power to both wire feed unit 18 and torch 2. Power supply 20 is power controlled and of the constant potential type.

In operation, an arc 4 is established between the consumable electrode 1 and the workpiece 5 by energizing the power supply 20 and delivering the electrode into direct contact with the workpiece. The arc voltage between the electrode and the workpiece remains substantially constant during the welding operation. Here, "substantially constant" means that the arc voltage varies no more than 5% from the set voltage during the welding process. The arc voltage set point is the point at which a stable arc is achieved. For example, 0.023 inch (0.6mm)
For wires in diameter, stable workpieces are 24~
realized using an arc voltage of 30V and
For 0.035-0.052 inch (0.89-1.32 mm) diameter wire, a stable arc is achieved using an arc voltage of 35-51V. The consumable arc electrode is
The welding torch is introduced into the arc through the contact tube 16 and the metal is transferred from the electrode to the workpiece.

The electrode 1 is introduced through the contact tube 16 into the arc 4 formed between the electrode 1 and the workpiece 5 . The contact tube 16 is connected via a torch to a power source 20 for supplying power to the electrode 1 . The workpiece 5 is connected to the ground in common with the power supply. Preferably, the torch 2 is held at a distance above the workpiece 5 to ensure an electrode extension distance or torch-workpiece distance X. 0.023 inch (0.6
mm) diameter electrode, the preferred electrode extension distance is in the range of 3/8 to 3/4 inch (9.5 to 19 mm);
Most preferably about 5/8 inch (15.9mm);
and for 0.035 to 0.052 inch (0.9 to 1.3 mm) direct wire, the preferred electrode extension distance is 3/4
~1-1/2 inch (19-38 mm), most preferably about 1 inch (25.4 mm).

The arc is shielded from the surrounding atmosphere by a gas mixture consisting essentially of (A) 3-8% carbon dioxide, (B) 30-40% argon, and (C) the balance helium.

Returning to FIG. 1, the shielding gas or shielding gas mixture useful in the present invention is prepared in gas mixer 22, which receives component gases from cylinders 24, 25, and 26. For example, cylinder 24 contains argon, cylinder 25 contains carbon dioxide, and cylinder 26 contains helium. Any other suitable gas storage container, such as a storage tank, may also be used in conjunction with the present invention. Gas mixer 22 can be any conventional gas mixer that can be configured to meter the appropriate gases from each gas source to establish the gas mixture useful in the present invention.

The shielding gas mixture useful in the present invention flows through the conduit means 6 to the torch 2 and through the space 27 between the contact tube 16 and the torch cup 28 to provide protection for shielding the arc 4 from the surrounding atmosphere. Form a shield. The torch cup 28 preferably projects beyond the front end 17 of the contact tube 16 such that the contact tube is recessed a distance y inside the torch cup. Preferably, distance y is at least 5/32 inch (3.9 mm).

In the past, achieving high deposition rates with stability required working in a rotating spray arc mode. Figures 2, 3 and 4 are graphical representations of the stable weld range for 0.023 inch (0.6 mm), 0.35 inch (0.9 mm) and 0.045 inch (1.1 mm) diameter wires, respectively. 2, 3 and 4, curve A represents the stability area for conventional gas metal arc welding, curve C represents the stability area for gas metal arc welding in the rotary spray arc mode, and curve D represents the stability area for gas metal arc welding in the rotary spray arc mode. Figure 3 represents the stability region for gas metal arc welding of the present invention in directional spray arc mode. In Figures 3 and 4, additional curve B is shown in U.S. Pat.
4645903 represents the stability region for the improved gas metal arc welding process disclosed in No. 4,645,903. The shield gas compositions used to illustrate the invention and generate the data reported in Figures 2-4 are:
It consisted of 61% helium by volume, 35% argon by volume and 4% carbon dioxide by volume. Deposition rate measurements were made over a wide range of wire feed rates that resulted in stable axial spray for the diameters illustrated.

As can be seen from the graphs in Figures 2, 3 and 4,
The gas metal arc welding process of the present invention includes:
Approximately 151b/ for a 0.023 inch (0.6mm) diameter electrode
Enables stable welding rates in axial spray mode up to 6.75Kg/hr (6.75Kg/hr),
Also 0.035 inch (0.9mm) and 0.045 inch (1.1
mm) diameter electrode allows a significantly increased deposition rate in the axial spray mode, which is higher than in other gas metal arc welding processes and even in the rotary spray arc mode.

ADVANTAGES OF THE INVENTION Through the use of the process and the use of gas mixtures of the present invention, spray mode gas metal arc welding has now become possible in an improved manner. In particular, it has become possible to carry out gas metal arc welding in the preferred axial spray arc mode at higher and more stable deposition rates than heretofore possible using other known gas metal arc welding methods.

Although specific examples of the invention have been described above, it should be noted that many changes may be made within the scope of the invention.

[Brief explanation of the drawing]

FIG. 1 shows an overview of welding equipment useful in carrying out the method of the invention. FIG. 2 is a graph comparing the deposition rate performance of the present process as well as that of other known methods in an axial spray mode using 0.023 inch (0.6 mm) diameter wire. FIG. 3 is a graph comparing the deposition rate performance of the process of the present invention in an axial spray mode using 0.035 inch (0.9 mm) diameter wire as well as the deposition rate performance of other known methods. Figure 4 shows
1 is a graph comparing the deposition rate performance of the present process as well as that of other known methods in an axial spray mode using 0.045 inch (1.1 mm) diameter wire; 1: wire, 2: arc welding torch, 3: drive motor, 4: arc, 5: workpiece, 6: conduit means, 12: reel, 14: feed roll, 16: contact tube, 18: wire feeding unit, 20: Power supply,
22: Gas mixer, 24-26: Cylinder, 27:
Space, 28: Torch cup.

Claims (1)

Claims: 1. A method for axial spray mode gas metal arc welding using a consumable wire electrode having a diameter in the range of 0.023 to 0.052 inches (0.58 to 1.3 mm), comprising: (a ) forming an arc between the consumable wire electrode and the workpiece; and (b) maintaining a substantially constant arc voltage between the wire electrode and the workpiece in the range of 24 to 51V. (c) feeding the consumable wire electrode into the arc through a welding torch contact tube, where the welding torch contact tube is 0.5 to 1.5 inches (12.7 to 38.1 mm) wide.
A welding torch with a torch cap that maintains a distance away from the workpiece and extends the welding torch contact tube beyond the tip of the contact tube by at least 5/32 inch (3.97 mm) to allow for electrode extension of at least 5/32 inch (3.97 mm) (d) transferring metal from said wire electrode to a workpiece;
(e) converting said arc to (A) 3-8% by volume carbon dioxide, (B) 30-40% by volume argon, and ( C) axial spray mode gas metal arc welding process comprising shielding with a gas mixture consisting balance helium.