JP2544214B2 - Welding voltage control method in four-source gas welding - Google Patents

Description

TECHNICAL FIELD The present invention relates to a welding voltage control method in four-source gas welding.

(Prior art) Conventionally, A is generally used as a shield gas during welding.
Although r and Co ₂ are used, in recent years, quaternary gas welding in which He, O _{2 and the} like are added has been performed.

As a welding method using such a shield gas, for example, there is a consumable electrode type arc welding method. As shown in FIG. 3, a tip 22 as an electrode is provided around an electrode wire 21 as a core, and a shield gas 24 is passed between the tip 22 and a nozzle 23 having an annular outer periphery. Thus, the welding base material 25 is prevented from being oxidized when a droplet is dropped from the arc 26 at the tip of the electrode wire 21 and the welding metal 27 is welded.

Since the shielding gas is generally Ar and CO ₂ in the past, the arc rotates and becomes unstable in a high current region, but when He is contained, the arc rotation is stable. Also, O ₂
Is used for accelerating the melting reaction of metals, and when it is too much, the amount of metal oxides increases, but quaternary gas with these added has come to be used for shielding.

(Problems to be solved by the invention) For droplet transfer in four-source gas welding, there are an axial spray in which fine droplets drip directly below and a rotating spray in which fine droplets drip in the rotating direction as the arc rotates. is there. When the welding voltage is low with respect to an arbitrary current, the axial spray is produced, and when the welding voltage is high, the rotating spray is produced. That is, the droplet transfer form changes from the axial spray to the rotating spray at a certain voltage.

However, in the case of four-source gas welding, the rotating spray region has advantages over the axial spray region in that the arc is more stable, there is less spatter, and a wider penetration can be obtained. Even within the region, the lower voltage has the advantage that undercutting is less likely to occur. In other words, the proper voltage in the quaternary gas welding is a low voltage region in the rotating spray region, which is close to the boundary with the axial spray region, so if the voltage becomes low due to variations in the protrusion length,
The transfer form may change from a rotating spray to an axial spray, the melting shape of the bead may change, and problems such as defective melting may occur. At present, the voltage is not controlled in such a case.

That is, the waveforms of the welding voltage during axial spraying and rotating spray are as shown in Fig. 4 (a) and (b), and the voltage always fluctuates greatly with axial spraying (0.3 to 0.5 V in the diagram). On the other hand, it was found that the rotating spray was almost constant.

In view of this, the present invention has been made in order to solve the drawbacks of the prior art by providing a welding voltage control method in quaternary gas welding that can always maintain an appropriate voltage.

(Means for Solving the Problems) In order to achieve the above object, the present invention divides the welding voltage at a fixed time into N with respect to time in welding using a quaternary gas, and welds in each of the N divided sections. While obtaining the difference between the maximum value and the minimum value of the voltage, the difference is equal to or greater than a predetermined set value, when the welding voltage continues to rise by a certain value when the preset number of times continues. The feature is that welding is always performed in the area of the rotating spray that is continuous with the axial spray.

(Examples) The present invention will be described below with reference to the examples shown in FIGS. 1 and 2.

The welding voltage control method in the four-way welding according to the present invention will be described, for example, in the case of using a voltage control device as shown in FIG. 1. In the nozzle 2 supported by the welding robot 1 so as to be vertically movable. Wire feeding means 3 to wire 4
Will be sent.

Then, the wire 4 is fed through the welding power source 6 according to a command from the robot controller 5.

Further, the adjustment of the raising and lowering of the nozzle 2 is operated by a command from the robot controller 5 and the welding power source 6.

Below the nozzle 2, there are a work 7 to be welded and a table 8 on which the work 7 is placed. Below the table 8, a welding power source 6 and a cord 9 are connected.

A container 10 for a quaternary gas such as Ar, CO ₂ , He and O ₂ is connected to a welding power source 6.

The voltage controller 11 includes a voltmeter 12, a low pass filter 13,
It is composed of an A / D converter 14, a controller main body 15, an interface 16 and the like, and is connected to the robot controller 5 with the interface 16.

The voltmeter 12 measures the positive voltage on the nozzle 2 side and the negative voltage on the table 8 side.

Next, a voltage control method for quaternary gas welding shown in FIG. 2 in such an apparatus will be described with reference to a flowchart.

When the workpiece 7 is placed on the table 8, the nozzle 2 is set above the workpiece 7, and welding is started, Va = robot input value is determined as the setting of the initial voltage.

Next, the continuous abnormality check counter is reset,
Let N = 0.

Then, the voltage waveform of one cycle of weaving is captured. Here, when weaving, the effect appears on the voltage waveform, so apply a filter according to the weaving frequency to eliminate the voltage change due to weaving and A / D
The converter 14 performs analog and digital conversion.

Next, the control device main body 15 divides the captured voltage waveform into a large number, for example, 64, and the respective voltages are read. Obtain the maximum value (Vmax) and minimum value (Vmin) of the read voltage.

The presence or absence of an abnormality is checked by taking the voltage change at this time. If Vmax-Vmin> 0.5 (V), the continuous abnormality check count N = N + 1, and if Vmax-Vmin≤0.5 (V), If there is, reset N of the continuous abnormality check counter
Return to = 0.

If N ≧ 10 in the check of the number of continuous abnormalities, the voltage is increased to Va = Va + 0.5 (V), and the robot controller 5 is instructed to set the initial voltage again.

If N <10, the voltage waveform of one weaving cycle is captured again.

In the embodiment of the present invention, the case where the welding robot is used has been described, but it goes without saying that the welding robot is not necessarily limited to the welding robot and manual welding may be used.

(Effects of the Invention) As described above, in the present invention, when welding using a quaternary gas, when the fluctuation of the voltage is equal to or higher than a specific voltage within a certain period of time and is equal to or more than a set number of times, Since a constant appropriate voltage is controlled by issuing a raising command, fusion defects can be prevented and spatter can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view showing a voltage control device in four-source gas welding according to the present invention, FIG. 2 is a flow chart of a four-source gas welding voltage control method using FIG. 1, and FIG. FIG. 4 is an explanatory diagram of a gas shield consumable electrode type arc welding method which has been conventionally used, and FIG. 4 is a waveform diagram of welding voltage at the time of axial spraying and rotating spraying. 1 ... Welding robot, 2 ... Nozzle, 3 ... Wire feeding means, 4 ... Wire, 5 ... Robot controller, 6
...... Welding power supply, 7 ...... Workpiece, 8 ...... Stand, 9 ...... Code, 10 ...... Container, 11 ...... Voltage control device, 12 ...... Voltmeter,
13 …… Low-pass filter, 14 …… A / D converter, 15 ……
Controller main body, 16 ... Interface.

Claims (1)

(57) [Claims] 1. In welding using quaternary gas, the welding voltage at a fixed time is divided into N with respect to time, and the difference between the maximum value and the minimum value of the welding voltage in each of the N divided sections is obtained, When the difference is equal to or greater than the preset value and continues for the preset number of times or more, the welding voltage is increased by a certain value to always perform welding in the area of the rotating spray that is continuous with the axial spray. A welding voltage control method in quaternary gas welding, characterized in that.