JP2003220467A - Method for treating crater formed on aluminum welding part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce correction processes after welding and form a welding bead having stable quality at a time. <P>SOLUTION: After welding to the aluminum part, the discharge condition of the shield gas is held, and the energization is temporarily stopped to the electrode chip 22 for prevention of arc generation (see figure 3A). After cooling the crater 2, the stopping condition of energization to the electrode chip 22 is released and the current is applied again for arc generation, build up welding to the crater 2 is done (see figure 3B), and the build up welded part is cut for flattening (see figure 3C). <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of treating a recess formed in an aluminum weld for correcting a recess formed in the aluminum weld by arc welding, for example.

[0002]

2. Description of the Related Art Conventionally, MIG WELDING is known which enables high quality welding of stainless steel, heat resistant alloys, copper alloys, aluminum alloys and the like. In this MIG welding, an arc is generated between a wire and an object to be welded in an atmosphere of a shield gas, and the aluminum alloy is welded by sequentially feeding the wire as the wire is melted by the generated arc. , Gas shield consumable electrode type arc welding method.

For example, when argon is used as a shielding gas and MIG welding is performed on an aluminum alloy,
The surface temperature of the weld becomes high due to the removal of the oxide film formed on the surface of the weld under the cleaning action of the arc. Part occurs.

Here, the cause of the crater-like depressions will be described in detail.

Aluminum itself melts at a temperature of about 660 ° C., but an oxide film is formed on its surface. The main component forming the oxide film is alumina, and in order to melt this alumina, the temperature is about 2000 ° C.
Unless the heating temperature is raised up to this point, the oxide film cannot be removed and the base material (aluminum) coated with the oxide film cannot be melted.

Therefore, in the MIG welding, in order to remove the oxide film, the arc gas is ignited by the argon gas discharged as the shield gas to raise the heating temperature. At this time, the attitude of the welding torch needs to be maintained at the torch angle in the forward direction along the welding instruction point.

Therefore, as shown in FIG. 4A, when the welding work is started from the welding start point P1 toward the welding end point P2, the base metal is melted in the forward direction from the target position after the arc is generated, and the target position is reached. The base material is melted by advancing along the traveling direction (direction of the welding end point P2) while forming the weld bead 1 at the rear side (see FIG. 4B).

At the end position of the welding bead, that is, when the welding operation proceeds to the welding end point P2 and the welding operation is ended at that position, the crater-like recess 2 remains at the welding end point P2 ( See FIG. 4C).

In the prior art, since the crater-shaped recess 2 thus generated causes, for example, welding cracks, cracks, etc., after the welding work is completed, the crater-like recesses 2 are formed manually by the operator. A welding operation of embedding the recessed portion 2 and embedding it therein is performed, and a correction operation of making it flat by polishing or the like is performed.

[0010]

However, in the correction method for the crater-shaped depressions according to the prior art, it is necessary to remove the oxide film covering the crater-shaped depressions when performing the overlaying work. However, there is a problem in that the crater-shaped recessed portion is heated to a high temperature (about 2000 ° C.), and further melt-through of the welding bead is likely to occur.

Further, in the conventional method for correcting the crater-like depressions, since the build-up work is a manual work performed by the operator, the finish thereof varies and
There is a problem that overfilling occurs.

The present invention has been made in consideration of the above-mentioned various problems, and an aluminum welded portion capable of forming a weld bead having a stable quality while reducing the correction man-hour after the welding is completed. It is an object of the present invention to provide a method of treating a recess formed in the.

[0013]

In order to achieve the above-mentioned object, the present invention provides a wire that melts with respect to the base material by generating an arc between the electrode and the base material while discharging a shielding gas. Is a method for treating the recess formed at the terminal end of the welded portion of the base metal when MIG welding is performed through, after completion of welding to the welded portion of the base metal made of aluminum or aluminum alloy, While maintaining the discharge state of the shield gas, the energization of the electrodes is temporarily stopped to prevent the arc from being generated, and the recess formed in the aluminum weld is cooled.

Therefore, since the arc is prevented from being generated by temporarily stopping the energization to the electrodes, an oxide film is not formed in the recess formed at the end of the aluminum welding portion, and The oxidation rate can be delayed by cooling the recess.

Subsequently, the state where the current supply to the electrode is stopped is released and the current is supplied again to generate an arc, and welding is performed to embed the recessed portion through the melting wire.

[0016] According to the present invention, when welding is performed by embedding the recessed portion and overlaying the recessed portion, an oxide film is not formed on the recessed portion, so that it is not necessary to heat to a high temperature in order to remove the oxide film. It is possible to prevent the welding bead from burning through.

Further, according to the present invention, the welding nozzle is held by the arm of the welding robot, and the welding robot is controlled based on the teaching data input to the welding robot. And a weld bead with a stable quality is formed.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Regarding the method for treating a recess formed in an aluminum welded portion according to the present invention, preferred embodiments will be given in connection with a welding nozzle for carrying out the method, and the accompanying drawings will be referred to. However, a detailed description will be given below.

In FIG. 1, reference numeral 10 indicates a welding nozzle for carrying out a method of treating a recess formed in an aluminum weld according to an embodiment of the present invention.

This welding nozzle 10 is applied to MIG welding, and is held by an arm 14 of a welding robot 12 provided so as to be displaceable in a multi-axis direction including three XYZ axes (FIG. 2). reference). A shield gas is discharged from an opening 16 on one end side of the welding nozzle 10 through an inert gas supply means (not shown), and a wire 20 is opened through the pair of feed rollers 18a and 18b. Is fed from the base metal to the base metal side.

An electrode tip 22 for covering the wire 20 is provided inside the welding nozzle 10, and a predetermined voltage is applied to the electrode tip 22 by a power source (not shown). In this case, the wire 20 is energized through the electrode tip 22, and the tip of the wire 20 protruding from the welding nozzle 10 by a predetermined length and the base material (aluminum).
An arc is generated between and. Therefore, the generated arc is provided to ignite a shield gas such as argon or helium to melt the surface of the base material and to melt a predetermined portion of the wire 20 protruding from the welding nozzle 10. .

Next, using the welding nozzle 10, M
The process of performing IG welding will be described below. In this embodiment, aluminum is used as the base material and argon gas is used as the shield gas. Further, the same steps as those of the above-mentioned conventional technique will be described using the same reference numerals.

In this case, as shown in FIG. 2, the welding nozzle 1 is attached to the arm 14 of the welding robot 12.
0 is held at a predetermined torch angle, and the arm 14 of the welding robot 12 is freely controlled based on the teaching program input in advance.

As shown in FIG. 4A, the welding nozzle 10 is advanced from the welding start point P1 of the object to be welded toward the welding end point P2 under the control of the arm 14 of the welding robot 12 to carry out the welding operation. Let it start. At that time, the argon gas is projected toward the base material from the opening 16 on the one end side of the welding nozzle 10 via a gas supply means (not shown), and the wire 20 is energized via the electrode tip 22 to The argon gas is ignited through an arc generated between the tip of the nozzle 20 and the base material.

Therefore, the base material is melted in the forward direction from the target position after the arc is generated, and the welding bead 1 is formed behind the target position.
The base material is melted by advancing the welding nozzle 10 along the advancing direction (direction of the welding end point P2) while forming (see FIG. 4B).

When the welding operation is completed at the terminal position of the welding bead 1, that is, the welding operation has reached the welding end point P2 and the welding operation is finished at that position, the electrode chip 22 is energized with the argon gas being discharged. It is stopped for a time (for example, about 1 to 2 seconds) (see FIG. 3A).

In this case, the crater-shaped recess 2 remains at the welding end point P2, but the electrode tip 22
Since the energization to the is stopped and the generation of the arc is prevented, the oxide film is not formed on the surface of the crater-shaped recess 2. Moreover, since the crater-shaped recess 2 is cooled by the argon gas discharged from the opening 16 on the one end side of the welding nozzle 10 (for example, the surface temperature is reduced from about 2000 ° C. to about 600 ° C.), the crater. It is possible to delay the rate at which the surface of the concave portion 2 is oxidized.

When the power supply to the electrode tip 22 is stopped, argon gas having a flow rate of about 1 liter per minute is discharged, the power supply to the electrode tip 22 and the power supply to the electrode tip 22 are stopped, and the supply and the stop of the supply of the argon gas are performed. The discharge flow rate and the like are all controlled by a teaching program previously input to the welding robot 12.

Subsequently, in the above-mentioned state in which an oxide film is not formed on the surface of the crater-shaped depression 2, as shown in FIG. 3B, the electrode tip 22 is again energized to generate an arc, A welding operation for filling the crater-shaped recess 2 with the wire 20 that melts is performed. The welding time for the crater-shaped recess 2 is about 1.5.
It is carried out within a range of up to 2 sec, and argon gas having a flow rate of about 1 liter per minute is discharged during the welding operation.

Therefore, after the melted wire 20 is applied to the crater-shaped recess 2 by a predetermined amount,
The correction work for the welded part is completed by cutting the built-up portion into a flat shape by a polishing means or a cutting means (not shown) (see FIG. 3C).

As described above, in the method of treating the recess formed in the aluminum welded portion according to the present embodiment, the energization of the electrode tip 22 is temporarily stopped at the end position (welding end point P2) of the welding bead 1. By keeping the argon gas discharged, the arc is prevented from being generated and the oxide film is prevented from being formed on the surface of the crater-shaped recess 2.

Therefore, in the correction work for temporarily releasing the state where the power supply to the electrode tip 22 is stopped and welding the buildup to the crater-shaped recess 2, the oxide film is formed on the crater-shaped recess 2. High temperature (about 20
It is not necessary to heat the bead 1 to 00 ° C., and the weld bead 1 can be prevented from melting through.

Further, in the prior art, the correction work is performed manually by the operator, but in the method of processing the recessed portion formed in the aluminum welded portion according to the present embodiment, it is input to the welding robot 12 in advance. By performing the teaching program based on the teaching program, the finish does not vary and it is possible to prevent overfilling.

[0034]

According to the present invention, the following effects can be obtained.

That is, when welding is performed by embedding the recessed portion and overlaying the recessed portion, since the oxide film is not formed in the recessed portion, it is not necessary to heat to a high temperature in order to remove the oxide film, and the welding bead It is possible to prevent burn-through, reduce correction man-hours after welding, and form a weld bead with stable quality.

[Brief description of drawings]

FIG. 1 is a longitudinal cross-sectional view taken along the axial direction of a welding nozzle that implements a method of treating a recess formed in an aluminum weld according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a state where the welding nozzle shown in FIG. 1 is held by an arm of a welding robot to perform welding.

3A to 3C are explanatory views showing a process for treating a recess formed in an aluminum weld using the welding nozzle shown in FIG. 2, respectively.

4A to 4C are explanatory views showing a MIG welding process according to a conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Weld bead 2 ... Crater-shaped depression 10 ... Welding nozzle 12 ... Welding robot 14 ... Arm 16 ... Opening 20 ... Wire 22 ... Electrode tip

Claims (2)

[Claims] 1. An arc is generated between an electrode and a base material while discharging a shielding gas, and when MIG welding is performed through a wire that melts to the base material, a welding site of the base material In the method for treating the recess formed in the terminal portion, after the welding of the welding portion of the base material made of aluminum or aluminum alloy is completed, the energization of the electrode is temporarily performed while maintaining the discharge state of the shield gas. A step of stopping the generation of an arc to stop the generation of the arc, cooling the recess formed in the aluminum weld, and releasing the energization stop state to the electrode to re-energize to generate the arc and melt. And a step of performing welding for embedding the recessed portion through a wire for forming the recessed portion formed in the aluminum welded portion. 2. The method according to claim 1, wherein an arm of the welding robot holds a welding nozzle, and the welding robot is controlled based on teaching data input to the welding robot. And a method of treating a recess formed in an aluminum weld.