JPH0420710B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a method for detecting the amount of groove width variation of a welded material to be welded by a rotating arc welding method. This invention relates to a method for detecting the amount of groove width fluctuation of a welded material, which can detect the amount of groove width fluctuation with high precision and in real time without using a special groove width detector. .

[Prior art and its problems]

A rotating arc welding method is known as a welding method.

In this rotary arc welding method, the welding wire is guided out from a rotating nozzle that rotates at high speed around its axis by being deviated from the axis of the rotating nozzle, and is supplied into the groove together with shielding gas. A rotating arc is generated between the tip and the welding bead, which forms a weld bead within the groove and welds the materials to be welded. The rotating nozzle is moved in the welding direction along the groove while rotating at high speed around the axis.

According to this type of rotating arc welding method, since the arc rotates, the physical effect of the arc is dispersed to the surrounding area, and good welding with distributed and flattened weld bead penetration can be achieved. It can also be made faster.

By the way, when welding materials to be welded, if the groove width of the materials to be welded changes, the height of the weld bead within the groove and the penetration of the weld bead into the side wall of the groove will change, making it difficult to achieve good welding. become unable. Therefore, in order to perform good welding, even in the rotating arc welding method, it is necessary to detect the amount of variation in the groove width and change welding conditions such as welding speed according to the amount of variation in the groove width. be.

For this reason, we have developed a method for detecting the amount of variation in groove width that can detect the amount of variation in groove width with high accuracy and in real time when welding materials to be welded using the rotating arc welding method. is desired, but
A detection method with such characteristics has not yet been proposed.

[Purpose of the invention]

This invention utilizes the characteristics of the rotating arc itself to detect groove width fluctuations with high precision and in real time without using a special groove width detector. The purpose of this invention is to provide a variation detection method.

[Summary of the invention]

In the present invention, a welding wire is guided out from a rotating nozzle directed toward a groove of a material to be welded while being deviated from the axis of the rotating nozzle, and the welding wire is supplied into the groove together with a shielding gas, and The rotating nozzle is rotated at high speed around the axis to generate a rotating arc between the welding wire and the groove, and the rotating nozzle is moved in the welding direction of the groove, thereby When welding the material to be welded by placing a welding bead in the groove, the voltage waveform of the arc is continuously detected, and from the voltage waveform, it is determined that the arc is in contact with the rotating nozzle per revolution of the arc. To obtain voltage waveforms of a predetermined width in four rotation ranges: a rotation range to the rear, a rotation range to the left, a rotation range to the front, and a rotation range to the right when facing forward in the welding direction from the axis. dividing the voltage waveform, extracting voltage waveforms in the left rotation range and right rotation range from the divided voltage waveforms, and further dividing each of the voltage waveforms in the two extracted rotation ranges. Detect the peak voltage value at
The present invention is characterized in that the amount of variation in the width of the groove is determined from the amount of variation in one or both of the peak voltage values detected in this manner.

[Structure of the invention]

Hereinafter, the detection method of the present invention will be explained in detail based on the drawings.

FIGS. 1a and 1b are explanatory diagrams showing the principle of the detection method of the present invention.

In Figures 1a and b, 2 is a horizontal groove, and the groove width of groove 2 in Figure 1a is G ₁ , and in Figure 1b
The groove width of the groove 2 is _G2 , which is larger than _G1 , and the groove 2 in FIG. 1b is wider than the groove 2 in FIG. 1a. Reference numeral 1 denotes a rotary nozzle directed toward the groove 2 from above, and 3 a rotary nozzle deviated from the axis 1a of the rotary nozzle 1 and led out, and supplied into the groove 2 together with shielding gas from a gas supply means (not shown). The welding wire 4 is an arc generated between the welding wire 3 and the groove 2. The rotary nozzle 1 moves the groove 2 in the welding direction (from the back side to the front side of the paper in FIGS. 1a and 1b) while rotating at a high speed around the axis 1a at a rotational speed on the order of several tens of Hz. In this way, the arc 4, which rotates as the rotary nozzle 1 rotates, forms a weld bead 6 within the groove 2, and welds the material to be welded 7.

FIG. 2 is a rotational position diagram showing the rotational position of the above-mentioned rotating arc. As shown in FIG. 2, when the arc 4 and therefore the welding wire 3 are directed forward in the welding direction 8 and are at the rear end from the axis 1a of the rotating nozzle 1, it is referred to as C _r ; A certain moment is defined as C _f , a moment at the left end from the axis 1a is defined as L, and a moment at the right end is defined as R.
As shown by arrow 9, arc 4 is, for example, C _r →L
→C _f It is rotating in the direction of →R.

For example, when a constant current power source is used as the power source for generating such a rotating arc 4, when the width of the groove 2 widens from G1 in Figure _1a to G2 in Figure _1b , The voltage changes of the arc 4 at rotational positions C _r , L, C _f and R are as follows.

In other words, even if the groove width increases from G ₁ to G ₂ ,
Since the arc 4 is generated using a constant current, the protrusion length _le of the welding wire 3 does not change as shown in FIG. On the other hand, as the groove width of the bead 6 increases from _G1 to _G2 , the bead surface decreases from surface 6a to surface 6a' and the crater surface decreases from surface 6b to surface 6b'. The arc length l _a increases. Due to this increase in arc length l _a , the rotational position C _r ,
The voltage of the arc 4 at L, C _f and R increases.
Furthermore, at rotational positions L and R, the distances to the side wall 2 _L of the left groove 2 and the side wall 2 _R of the right groove 2 increase toward the front in the welding direction, so that The actual arc length of the arc 4 increases, and an increase in the voltage of the arc 4 due to the increase in the actual arc length is added. The voltage increase due to this increase in the actual arc length increases until the arc 4 no longer reaches the side wall portions 2 _L and 2 _R of the groove 2, and saturates at the point where the arc 4 no longer reaches the side wall portions 2 L and 2 R of the groove 2.

The arc voltage change due to the above groove width change is
This is illustrated and shown in FIG. Here, E _cr and E _cf represent the arc voltages at rotational positions C _r and C _f, respectively, and E _S represents the arc voltage at rotational positions L and R, that is, E _L and E _R
shows. The welding conditions are, for example, the rotation diameter of the welding wire 3 (rotation diameter of the arc 4) D: 6 mm, the rotation speed N of the rotating nozzle 1: 60 Hz, the welding current I: 300 A,
The supply speed v _f of the welding wire 3 is 11.5 m/min, and the welding speed v is 25 cm/min.

As shown in Fig. 4, when the groove width G changes,
Although the arc voltages E _cr , E _cf , and E _S vary,
The arc voltage change _ΔES at rotational positions L and R is
As mentioned above, the apparent arc length l _a of arc 4
It is the largest because it consists of the voltage change ΔE _SA due to the change in , and the voltage change ΔE _SK due to the change in the actual arc length of the arc 4. For example, when the groove width G increases from G ₁ = 12 mm to G ₂ = 14 mm, the arc voltage E _S at rotational positions L and R becomes E _S1 ≒
From 32.5V to E _S2 ≒34V, ΔE _S ≒1.5V also increases significantly. Therefore, if the arc voltage E _S at such rotational positions L and R is found and the magnitude of the change ΔE _S is known, then from the magnitude of the change ΔE S, the arc voltage E _S as shown in Fig. 4 can be calculated. The groove width variation amount of the groove 2 can be determined based on the relationship between the change in the tip width G and the change in the arc voltage _ES . Note that the above description also applies to the case where a constant voltage power source is used as the arc generating power source.

The present invention detects the amount of variation in groove width based on the above principle.

Therefore, in the present invention, first, the voltage waveform E of the arc 4 is detected as shown in FIG. Then, the detected voltage waveform E is divided in the manner shown in FIG. That is, per revolution of the arc 4, the center line 10 connecting the rotational positions C _r and C _f (located on the center line in the width direction of the groove 2) and the line 10' connecting the rotational positions L and R Angle φ ₀ from 5 to 90 degrees
The arc 4 is divided into a rotation range where the arc 4 is directed from the axis 1a of the rotary nozzle 1 toward the front in the welding direction 8 and the rotation range at the rear.
It is divided to obtain voltage waveforms of four rotation ranges: Z _cr , rotation range Z _L on the left, rotation range Z _cf on the front, and rotation range Z _R on the right.

Then, the divided rotation ranges Z _r , Z _L , Z _f and Z _R
From the voltage waveform at , extract the voltage waveforms in the rotation range Z _L where the arc 4 is on the left and the rotation range Z _R where the arc 4 is on the right, and use the peak hold circuit to calculate the voltage waveforms in the rotation range Z _L and Z _R , respectively. Detect the peak voltage value. By detecting such a peak voltage value, in the left rotation range Z _L , the arc voltage E _L at the rotation position L is
However, in the right rotation range Z _R , the arc voltage E _R at the rotation position R is obtained.

And the arc voltage E _L and E _R as above
are detected continuously to determine the amount of variation in the arc voltages E _L and E _R , and from one or both of these amounts of variation, the change in the groove width G and the arc voltage E are determined as shown in Fig. 4. Based on the relationship with the change in _S , the groove width variation amount of groove 2 is determined.

〔Effect of the invention〕

As explained above, in this invention, when welding materials to be welded by the rotating arc welding method, the voltage waveform of the rotating arc is detected, and the amount of variation in the groove width is detected based on this voltage waveform. Because there are
The amount of variation in groove width can be detected with high precision and in real time without using a special groove width detector.

[Brief explanation of drawings]

Figures 1a and b are explanatory diagrams showing the principle of the detection method of the present invention, Figure 2 is a rotational position diagram showing the rotational position of the rotating arc, and Figure 3 is the arc length due to changes in groove width. FIG. 4 is a graph showing changes in arc voltage due to changes in groove width. FIG. 6 is an explanatory diagram showing how to divide the arc voltage waveform. FIG. It is a graph showing a voltage waveform. In the drawings, 1...rotating nozzle, 1a...axis center, 2...bevel, 3...
Welding wire, 4... Arc, 6... Welding bead, 7...
Material to be welded, 8... Welding direction, 9... Rotation direction.

Claims (1)

[Claims] 1. A welding wire is deviated from the axis of the rotary nozzle and guided out from a rotating nozzle directed toward the groove of the material to be welded, and the welding wire is supplied into the groove together with a shielding gas, and rotating at high speed around the axis to generate a rotating arc between the welding wire and the groove, and moving the rotating nozzle in the welding direction of the groove;
As a result, when a welding bead is placed in the groove and the material to be welded is welded, the voltage waveform of the arc is continuously detected, and from the voltage waveform, it is determined that the arc rotates in the rotation direction per revolution of the arc. Obtain voltage waveforms of a predetermined width in four rotation ranges: a rotation range to the front, a rotation range to the left, a rotation range to the front, and a rotation range to the right in the welding direction from the axis of the nozzle. Divide the voltage waveform as follows,
extracting the voltage waveforms in the left rotation range and the right rotation range from the divided voltage waveforms, and further detecting the peak voltage value in each of the voltage waveforms in the two extracted rotation ranges, A method for detecting a variation in groove width of a welded material, characterized in that the variation in the groove width is determined from the variation in one or both of the peak voltage values detected in this manner.