JPH0420708B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method for controlling the swing width of a rotating nozzle in a rotating arc welding method.

[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 the axis at a deviation from the axis, and is supplied into the groove together with shielding gas. A rotating arc is generated between the groove and the weld 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.

By the way, when welding while applying a swinging motion to the rotating nozzle in the width direction of the groove, conventionally, control was only performed to align the center of swing of the rotating nozzle with the width direction of the groove. Control to change the dynamic width (amplitude) was not performed. Therefore, since the rotating nozzle oscillates at a constant period and oscillation width, it is difficult to deal with changes in the groove width, and there is a problem that welding defects are likely to occur on the side walls of the groove. Ta.

[Purpose of the invention]

In view of the above-mentioned current situation, this invention deals with changes in the groove width when welding the materials to be welded while applying rocking to the rotating nozzle, and eliminates welding defects on the side walls of the groove. It is an object of the present invention to provide a method for controlling the swing width of a rotating nozzle in a rotating arc welding method, which makes it possible to satisfactorily weld materials to be welded without causing the welding.

[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 While rotating the rotating nozzle at high speed around the axis, a rotating arc is generated between the welding wire and the groove, and the rotating nozzle is rotated in the width direction of the groove. The rotary nozzle is moved in the welding direction of the groove while being oscillated at a constant period and oscillation width with the center as the center of oscillation, thereby forming a weld bead within the groove and welding the target. When welding the welding material, the voltage waveform of the arc is continuously detected, and it is determined from the voltage waveform that the arc is directed forward and backward in the welding direction from the axis of the rotating nozzle per one rotation of the arc. The voltage waveform is divided so as to obtain voltage waveforms of a predetermined width in four rotation ranges: a certain rotation range, a rotation range on the left, a rotation range on the front, and a rotation range on the right. The voltage waveforms in the left rotation range and the right rotation range are extracted from the voltage waveform, and the peak voltage value in each of the extracted voltage waveforms in the two rotation ranges is detected, and the voltage waveforms of the rotation nozzle are detected. The peak of the voltage waveform in the two rotation ranges in one or both of the swing range on the left and the swing range on the right when the shaft center faces forward in the welding direction from the center of swing. The present invention is characterized in that the swing width of the rotating nozzle is changed so that one or both of the voltage values falls within a predetermined range with respect to a predetermined peak voltage reference value.

[Structure of the invention]

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

In this invention, fluctuations in the groove width are detected from voltage fluctuations of the rotating arc, and the swing width of the rotating nozzle is changed and controlled in accordance with the fluctuations in the groove width.

FIGS. 1a and 1b are explanatory diagrams showing the principle of detecting fluctuations in groove width.

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 rotates at high speed around the axis 1a at a rotation speed on the order of several tens of Hz, aligns the axis 1a with the widthwise center 2a of the groove 2, and moves in the welding direction (see Fig. 1 a, b). (from the back side of the paper to the front side). In this way, the arc 4, which rotates as the rotating nozzle 1 rotates, forms a weld bead 6 within the groove 2, and the workpiece 7 is welded.
to weld.

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, the weld bead 6 has a groove width of G ₁ to G ₂
Due to the increase in the bead surface from surface 6a to surface 6
a' and the crater surface decreases from surface 6b to 6b', so the apparent arc length l _a of arc 4 increases. This increase in arc length _la causes the arc voltage at rotational positions C _r , L, C _f and R to increase. 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 walls 2 _L and 2 _R of the groove 2,
It becomes saturated when it no longer reaches the target.

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 arc voltages at rotational positions C _r and C _f, respectively, and E _S represents arc voltages at rotational positions L and R, that is, E _L and E _R. The welding conditions are, for example, the rotation diameter D of the welding wire 3 (rotation diameter of the arc 4): 6 mm, the rotation speed N of the rotating nozzle 1: 60 Hz, the welding current I: 300 A, and the supply speed vf of the welding wire 3: 11.5 m/min. , welding speed v: 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, by determining the arc voltage E _S at such rotational positions L and R and knowing its fluctuations, it is possible to detect fluctuations in the groove width of the groove 2.

Therefore, 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. In other words, per rotation of the arc 4, the rotational position C _r and
A line 10 connecting C _f (located on the center line in the width direction of groove 2) and a line 10' connecting rotation positions R and L
The arc 4 is divided by an angle φ ₀ of 5 to 90 degrees centered on the welding direction 8 from the axis 1a of the rotating nozzle 1.
The voltage waveforms of the four rotation ranges are the rotation range Z _cr toward the front and the rear, the rotation range Z _L on the left, the rotation range Z _cf on the front, and the rotation range Z _R on the right. Divide as you like. Next, the divided rotation range
The peak voltage values of the voltage waveforms at Z _cr , Z _L , Z _cf and Z _R are detected by a peak hold circuit. By detecting such a peak voltage value, the rotational position C _r ,
The arc voltages E _cr , E _L , E _cf and E _{R at L, C f and R are} obtained.

Arc voltages E _cr , E _L , E _cf and E _R as above
The groove width fluctuation can be detected by continuously detecting the fluctuations in one or both of the arc voltages E _L and E _R at the rotational positions L and R. Note that the above description also applies to the case where a constant voltage power source is used as the arc generating power source.

In this invention, based on the above principle,
When the rotating nozzle swings in the groove width direction, fluctuations in the groove width are detected and the swinging width of the rotating nozzle is controlled as follows.

FIG. 7a is a cross-sectional view showing the groove in which the rotary nozzle is directed, the swing width of which is controlled by the method of the present invention, and FIG. 7b is the rotary nozzle in the groove of FIG. 7a. 8th plan view showing the movement locus of the axis of
Figure a is a cross-sectional view showing a groove wider than the groove shown in Figure 7a, and Figure 8b is a plan view showing the locus of movement of the axis of the rotating nozzle in the groove shown in Figure 8a.

In Figure 7 a, b and Figure 8 a, b, 1
2 is a horizontal groove. The groove width of the groove 12 in Fig. 7 a, b is G ₃ , and the groove width of the groove 12 in Fig. 8 a, b is G ₄ which is larger than G ₃ . The groove is wider than the groove 12 in FIGS. 7a and 7b.

Rotating nozzle 1 directed from above onto the groove 12
rotates at high speed around the axis 1a, and the groove 1
The groove 12 is oscillated in the width direction of the groove 12 with a constant period and a oscillation width (amplitude) W ₀ that matches the groove width G ₃ with the center of the width direction of the groove 12 being the center of oscillation 12a. Move in the welding direction shown by arrow 8.

As described above, the rotating nozzle 1 swings in the width direction of the groove 12 with the center of the swing in the width direction of the groove 12 as the swing center 12a.

As shown in Fig. 7a, the groove width of the groove 12 is
G ₃ In a constant steady state, the arc voltages E _L and E _R that are continuously detected differ depending on the swing position of the rotating arc 4. In other words, the rotating nozzle 1
Near the left swinging end near the left side wall 2 _L , the arc voltage E _L at the rotational position L becomes smaller due to the influence of the side wall 2 _L , but as it moves away from the side wall 2 _L , the effect disappears and it remains almost the same. value. Similarly, near the right swing end, the arc voltage E _R at the rotational position R becomes smaller due to the influence of the side wall portion 2 _R , but as it moves away from the side wall portion 2 _R , the influence disappears and the value remains approximately the same. In other words, E _L ≈E _R near the center of rocking, which is not affected by the side walls 2 _L and 2 _R. However, as shown in Figures 8a and b, when the groove width of the groove 12 increases to _G4 , the swing width is the same as in Figures 7a and b.
At W ₀ , the distance between the rotation center of the arc 4 (which is the axis 1a of the rotating nozzle 1) and the side walls 2 _L and 2 _R of the groove 12 at the left and right swing ends = (G ₄ - W ₀ )/2
becomes larger, so E _L and E _R do not become much smaller values than in the cases of a and b in FIG. 7.

FIGS. 9a and 9b are graphs showing the arc voltages E _L and _ER of an arc that oscillates while rotating at oscillating positions. Figure 9a is the groove width shown in Figures 7a and b.
In the case of _G3 , FIG. 9b shows the case of the groove width _G4 ( _G3 < _G4 ) shown in FIGS. 8a and 8b. In addition, the swing width W ₀ of arc 4 is 4 mm, the swing speed is 4 mm/sec,
The arc rotation speed is 50Hz.

As shown in Fig. 9a, the arc voltage E _L at the rotational position L shows a value of E ₀ near the center of oscillation, but only when the oscillation approaches the left end of the oscillation as described above. decreases to Similarly, the arc voltage E _R at the rotational position R decreases only when the swing approaches the right swing end. However, as shown in FIGS. 8a and 8b, when the groove width increases, the distance between the rotation center of the arc 4 and the side walls 2 _L and 2 _R of the groove 12 at the left and right swing ends as described above. =(G ₄ -W ₀ )/2 becomes large, so the arc voltages E _L and E R at the rotational positions L and _R do not decrease much at the left and right swing ends, as shown in FIG. 9b.

Therefore, E _L , E _R in each half period of oscillation
The change in groove width of the groove 12 can be detected by determining the sum (integral value) of E _L and E _R , and by variation in one or both of the sums E L and E R . Therefore, Figure 7 a, b
Set one or both of the sums of E _L and E _R for each half cycle of oscillation as the reference value when oscillating at an oscillation width W ₀ that matches the groove width G ₃ shown. If the swing width of the rotating nozzle 1 is changed so that one or both of the sums of E _L and E _R for each half cycle of swing fall within a predetermined range with respect to the set value, the groove width can be reduced. It is possible to control the swing width in accordance with the In this case, it is necessary to control the number of revolutions of the arc per oscillation cycle so that it remains constant even if the oscillation width changes (for example, keep the oscillation width and oscillation speed constant in proportion), but E _L When using the sum of (E _L −E ₀ ) and (E _R −E ₀ ) instead of , E _R ,
The above control is not necessary. In addition, instead of the total of E _L and E _R , the number of E _L and E _R that is less than the reference value E ₀ is counted, and the swing width is adjusted so that the counted number falls within a predetermined range relative to the set count number. may be changed.

〔Effect of the invention〕

As explained above, in the present invention, when welding materials to be welded by the rotating arc welding method, the rotating arc voltage waveform is detected, the fluctuation of the groove width is detected based on this voltage waveform, and the rotating nozzle Since the oscillation width of the groove is changed and controlled, it is possible to deal with changes in the groove width and to successfully weld the materials to be welded without causing welding defects on the side walls of the groove.

[Brief explanation of drawings]

FIGS. 1a and 1b are explanatory diagrams showing the principle of detecting groove width fluctuations when no rocking is applied to the rotating nozzle, which is the basis for detecting groove width fluctuations in the control method of the present invention; The figure is a rotational position diagram showing the rotational position of the rotating arc, Figure 3 is an explanatory diagram showing changes in arc length due to changes in groove width, and Figure 4 is changes in arc voltage due to changes in groove width. FIG. 5 is a graph showing the arc voltage waveform, FIG. 6 is an explanatory diagram showing how to divide the arc voltage waveform, and FIG. FIG. 7b is a cross-sectional view showing the groove with the rotating nozzle facing which width is controlled, and FIG.
is a cross-sectional view showing a groove wider than the groove in FIG. 7a, FIG. 8b is a plan view showing the movement locus of the axis of the rotating nozzle in the groove in FIG. 8a, and FIG. 9a
is a graph showing the relationship between the oscillating position of an arc that oscillates while rotating and the arc voltages E _L and _ER , and Fig. 9b shows a similar relationship with a wider groove than in Fig. 9a. This is a graph showing. 1... Rotating nozzle, 1a... Axis center, 2... Bevel, 2a
... Center in the width direction of the groove, 4... Welding wire, 4... Arc, 6... Welding bead, 6a, 6a'... Bead surface,
6b, 6b'... Crater surface, 8... Welding direction, 9...
Rotation direction, 12...bevel, 12a...center of swing.

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 While rotating at high speed around the axis, a rotating arc is generated between the welding wire and the groove, and the rotating nozzle is oscillated about the widthwise center of the groove in the width direction of the groove. The rotary nozzle is moved in the welding direction of the groove while being oscillated at a constant period and oscillation width as a center of motion, thereby forming a weld bead within the groove and welding the material to be welded. When welding, the voltage waveform of the arc is continuously detected, and based on the voltage waveform, it is determined that, per revolution of the arc, the rotation range where the arc is directed forward and backward in the welding direction from the axis of the rotating nozzle. The voltage waveform is divided so as to obtain voltage waveforms of a predetermined width for four rotation ranges: the rotation range on the left, the rotation range in front, and the rotation range on the right, and from the divided voltage waveforms. The voltage waveforms in the left rotation range and the right rotation range are extracted, and the peak voltage value in each of the extracted voltage waveforms in the two rotation ranges is detected, and the axis center of the rotary nozzle is determined. is the peak voltage value of the voltage waveform in the two rotation ranges in one or both of the swing range on the left and the swing range on the right when facing forward in the welding direction from the center of the swing. Rotation in a rotating arc welding method, characterized in that the swing width of the rotating nozzle is changed so that one or both of the rotating nozzles fall within a predetermined range with respect to a predetermined reference value of peak voltage. Nozzle swing width control method.