JPH11314154A - Plug welding method of aluminum work - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the welding strength of the plug welding of an aluminum work. SOLUTION: In this plug welding method, a joining process to form a lower bead 4 while moving an arc welding torch 3 having a consumable electrode 3a in the circumferential direction of a prepared hole 1a formed in an upper work 1, a filling process to form an upper bead 5 while moving the arc welding torch 3 in the circumferential direction of the prepared hole 1a, and a finishing process to fill a center recess of the upper bead 5 while moving the arc welding torch 3 to the position facing the center of the prepared hole 1a are successively achieved. In the beginning of the joining process, the ratio of the positive polarity is reduced, and the ratio of the positive polarity is gradually increased from the joining process to the filling process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a consumable electrode type arc welding torch, in which a work made of aluminum or an aluminum alloy, which is superposed one on top of the other, is filled in a lower hole for welding formed in an upper work. The present invention relates to a plug welding method for aluminum-based workpieces to be arc-welded.

[0002]

2. Description of the Related Art Conventionally, in this type of plug welding method, an arc welding torch is stopped at a position facing the center of a pilot hole, and arc welding is performed in reverse polarity by connecting a consumable electrode of the arc welding torch to a positive electrode of a DC power supply. I do.

[0003]

In an aluminum-based work made of aluminum or an aluminum alloy, the penetration depth of the bead is deeper in the opposite polarity than in the positive polarity, but the arc welding torch faces the center of the pilot hole. If left as it is, penetration into the root portion of the prepared hole (the corner of the bottom of the hole between the inner peripheral surface of the prepared work upper hole and the upper surface of the lower work) tends to be insufficient, while sufficient penetration into the root portion However, there is a possibility that the work below will burn off, and it is difficult to increase the welding strength.

In view of the above, the present invention has been developed to improve the welding strength of an aluminum-based workpiece in which sufficient penetration into the root portion of the pilot hole can be obtained without causing the lower workpiece to burn through. It is an object to provide a plug welding method.

[0005]

Means for Solving the Problems In order to solve the above problems,
The present invention relates to a plug welding method in which a consumable electrode type arc welding torch is used to perform arc welding on a work made of aluminum or an aluminum alloy, which is superimposed one on top of the other, so as to fill a pilot hole for welding formed in an upper work. A joining step of forming the lower bead while moving the arc welding torch in the circumferential direction of the prepared hole, a filling step of forming an upper bead while moving the arc welding torch in the circumferential direction of the prepared hole, and lowering the arc welding torch. Move to the position facing the center of the hole and sequentially execute the finishing process to fill the center depression of the upper bead, and use an AC power supply that can change the polarity ratio between positive polarity and reverse polarity as the power source for the arc welding torch. The polarity ratio is changed so that the ratio of positive polarity gradually increases from the joining process to the filling process.

[0006] By the movement of the arc welding torch in the circumferential direction of the pilot hole in the joining step, the heat input part of the arc moves along the root part of the pilot hole, and the lower layer bead sufficiently melts into the root part of the pilot hole. In this case, if the reverse polarity is maintained, there is a possibility that the lower work will burn through, but by gradually increasing the ratio of the positive polarity, the lower work will be prevented from burning.

[0007] Further, by the movement of the arc welding torch in the circumferential direction of the prepared hole in the hole filling step, the peripheral portion of the prepared hole is filled with the upper bead, and the hollow remaining in the center of the upper bead is filled in the finishing step. As a result, the pilot hole is buried so as to be substantially flat without excessive bulging at the center of the pilot hole, and post-processing is facilitated.

Further, since the ratio of positive polarity is increased in the hole filling step, the bead swelling property is improved, and the pilot hole is efficiently filled. In this case, it is advantageous to reduce the arc current in the filling process and increase the torch moving speed as compared with the joining process, thereby preventing the upper bead from being roughened or excessively overlaid.

Further, if the arc current is further reduced in the finishing step than in the filling step, the beads are gradually cooled, thereby preventing the occurrence of welding defects due to rapid cooling.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a state in which two plate-like works 1 and 2 made of aluminum or aluminum alloy are vertically overlapped and plug-welded, that is, a welding work previously formed on an upper work 1. Work 1 and 2 by filling the pilot hole 1a
3 shows a state in which the electrodes are arc-welded.

In plug welding, a consumable electrode type arc welding torch 3 such as a MIG welding torch, a MAG welding torch, or a carbon dioxide gas welding torch using an aluminum-based welding wire as the electrode 3a.
This is performed using The power source of the arc welding torch 3 is the electrode 3
The AC power supply has a variable polarity ratio between a positive polarity for applying a negative voltage to a and a reverse polarity for applying a positive voltage to the electrode 3a. FIG. 2A shows a positive polarity ratio of 0%.
2B shows a state where the ratio of positive polarity is 25%, and FIG. 2C shows a state where the ratio of positive polarity is 50%.
In the case of a work made of aluminum or an aluminum alloy, the penetration becomes deeper as the ratio of the positive polarity decreases, and the ridge of the bead becomes higher as the ratio of the positive polarity increases.

At the time of plug welding, first, an arc is generated by placing the arc welding torch 3 at the position shown in FIG. 1A facing the center of the prepared hole 1a, and from this position the prepared hole 1a is formed.
A preheating step is performed in which the workpiece is moved to a position shown in FIG. In the preheating step, as shown in FIG.
% And the arc current is set to a relatively high value (for example, 1
50A) and the torch moving speed is relatively low (for example, 8
0 cm / min). It is also possible to execute the preheating step while moving the arc welding torch 3 in the circumferential direction from the position facing the peripheral portion of the prepared hole 1a circumferentially separated from the starting point toward the starting point.

Next, the arc current is set to a value higher than that of the preheating step (for example, 180 A), and the arc welding torch 3 is moved to the position shown in FIG.
From the position shown in (b) of FIG. 2 (A), the joint is moved by one turn in the circumferential direction of the prepared hole 1a at a speed slightly higher than the preheating step (for example, 100 cm / min), and the joining step is executed. ) (D)
The lower bead 4 as shown in FIG. In the joining step, the heat input part of the arc moves along the root of the prepared hole 1a, and the lower bead 4 melts well into the root. Further, at the beginning of the joining step, the ratio of the positive polarity is set to a low value (for example, 8%) in order to improve the penetration. Therefore, when the arc welding torch 3 makes a half turn around the pilot hole 1a, the positive polarity ratio is increased to a larger value (for example, 16%).

Next, the arc welding torch 3 is moved another round in the circumferential direction of the prepared hole 1a from the position shown in FIG. e) An upper bead 5 as shown in (f) is formed. In the hole filling step, the ratio of the positive polarity is set to a larger value (for example, 24%) than in the joining process in order to improve the bead swelling property, and the ratio of the positive polarity is further increased when the arc welding torch 3 makes a half turn around the pilot hole 1a. To a larger value (eg, 32%). In order to prevent the upper bead 5 from being roughened or excessively overlaid, in the filling process, the arc current is set to a lower value (for example, 120 A) than in the joining process, and the torch moving speed is set to a speed higher than that in the joining process (for example, 120 cm / min).

When the hole filling step is completed, the arc welding torch 3 is moved from the position shown in FIG. 1A (f) to the position shown in FIG. 1A (g) facing the center of the prepared hole 1a. After stopping for a certain period of time, a finishing step of filling the central depression of the upper bead 5 is executed. Here, since the upper bead 5 is formed so as to fill the periphery of the prepared hole 1a, the prepared hole 1a is filled so as to be substantially flat in the finishing step, and post-processing is facilitated. In the finishing step, the ratio of the positive polarity is set to a larger value (for example, 48%) than in the filling step, and the arc current is reduced to a lower value (for example, 50 A) than in the filling step to prevent excessive build-up. The bead is gradually cooled to prevent the occurrence of welding defects due to rapid cooling.

[0016]

As is apparent from the above description, according to the present invention, the penetration of the pilot hole into the root portion can be improved, the welding strength can be improved, and the pilot hole can be made substantially flat. So that post-processing becomes easy.

[Brief description of the drawings]

1A is a diagram showing the progress of welding according to the present invention, and FIG. 1B is a diagram showing changes during welding among arc current, torch moving speed, and positive polarity ratio.

FIGS. 2A, 2B, and 2C are diagrams showing changes in bead shape due to changes in positive polarity ratio.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Upper work 1a Prepared hole 2 Lower work 3 Arc welding torch 4 Lower bead 5 Upper bead

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kimitsutoshi Fujishita 1-10-1 Shinsayama, Sayama City, Saitama Prefecture Honda Engineering Co., Ltd. (72) Inventor Yasunari Wakisaka 1-10-1 Shinsayama, Sayama City, Saitama Prefecture Honda Engineering Co., Ltd.

Claims (3)

[Claims] 1. A plug welding method in which a consumable electrode type arc welding torch is used to perform arc welding on a workpiece made of aluminum or an aluminum alloy, which is vertically overlapped, so as to fill a pilot hole formed in an upper workpiece. The arc welding torch moving in the circumferential direction of the pilot hole to form a lower bead, the arc welding torch moving in the circumferential direction of the pilot hole to form an upper bead, and a hole filling step of forming an upper bead. Move to the position facing the center of the pilot hole,
The finishing process to fill the center depression of the upper bead is executed in order, and the AC power source that can change the polarity ratio between positive polarity and reverse polarity is used as the power source for the arc welding torch. A method for plug welding of aluminum-based workpieces, wherein the positive polarity ratio is changed so as to gradually increase. 2. The plug welding method for an aluminum-based work according to claim 1, wherein the arc current is reduced in the hole filling step as compared with the joining step, and the torch moving speed is increased as compared with the joining step. 3. The method of claim 2, wherein the arc current is further reduced in the finishing step than in the filling step.