JPH0366067B2 - - 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 shaft center while being deviated from the shaft center, 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 rotates at high speed around its axis and moves in the welding direction of the groove.

By the way, when welding while applying swinging motion to the rotary nozzle in the width direction of the groove, conventionally, the center of swing of the rotary nozzle was only controlled to coincide with the widthwise center of the groove. Oscillation width (amplitude)
There was no control to change the . 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 led out from a rotating nozzle facing a groove while being deviated from the axis of the rotating nozzle, the welding wire is supplied into the groove together with a shielding gas, and the rotating nozzle is While rotating at high speed around the axis, an arc is generated between the welding wire and the groove, and the rotating nozzle is oscillated in the width direction of the groove, with the center of the width of the groove being the center of oscillation. In a rotating arc welding method, the rotating nozzle is moved in the welding direction of the groove while being oscillated at a constant period and oscillation width, thereby forming a weld bead within the groove,
detecting a voltage waveform of the arc, and dividing the voltage waveform into a half-cycle of rotation on the right side and a half-cycle of rotation on the left side when the arc faces forward in the welding direction from the axis of the rotating nozzle; Then, the waveform area of the voltage waveform in the right half cycle and the left half cycle of the divided rotation is determined, and the difference between the waveform areas is determined to determine whether the axis of the rotating nozzle is aligned with the oscillation. The number of times the difference in the waveform area exceeds a preset reference value of the waveform area in each of the half-cycle of the oscillation on the right side and the half-cycle of the oscillation on the left side when facing forward in the welding direction from the center is counted. , and the swing width of the rotating nozzle is changed in each half cycle of the swing so that the count number falls within a predetermined range with respect to a preset reference value of the count number. It has the following.

[Structure of the invention]

Hereinafter, a method for controlling the swing width of a rotating nozzle in the rotating arc welding method of the present invention will be described in detail with reference to the drawings.

FIG. 1a is a cross-sectional view showing a groove with a rotating nozzle whose swing width is controlled by the method of the present invention, and FIG. 1b is a cross-sectional view of the rotating nozzle in the groove of FIG. 1a. A plan view showing the locus of movement of the axis of
2 is a cross-sectional view showing a groove wider than the groove in FIG. 1a, and FIG. 2b is a plan view showing the locus of movement of the axis of the rotating nozzle in the groove in FIG. 2a.

In Figure 1 a, b and Figure 2 a, b, 2
is the horizontal groove. Bevel 2 in Figure 1 a and b
The groove width of groove ₂ in Figure 2 a, b is G which is larger than G ₀ , and the groove width of groove 2 in Figure 2 a, b is the groove width of Figure 1 a, b. The groove is wider than 2. 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). welded wire,
4 is an arc generated between the welding wire 3 and the groove 2. The rotating nozzle 1 rotates at a high speed around an axis 1a at a rotational speed of several tens of Hz, and rotates at a constant period and width in the width direction of the groove 2, with the width direction center 2a of the groove 2 as the center of oscillation. The groove 2 is moved in the welding direction shown by the arrow 5 while swinging at a swing width (amplitude) W ₀ that matches the opening width G ₀ . In this way, a weld bead (not shown) is formed in the groove 2 by the arc 4 which rotates due to the rotation of the rotary nozzle 1.
The material to be welded 6 is welded.

FIG. 3 is a rotational position diagram showing the rotational position of the above-mentioned rotating arc. As shown in Fig. 3, when the arc 4 and therefore the welding wire 3 are directed forward in the welding direction 5 and are at the rear end of the rotating nozzle 1 in the welding direction, Gr is defined, and when the arc 4 and the welding wire 3 are at the forward end in the welding direction, conversely, is Cf, and the axis 1a of the rotating nozzle 1 is
When it is on the left side, it is called L, and when it is on the right side, it is called R. The arc 4 is rotating in the direction of Cr→L→Cf→R, for example, as shown by an arrow 7.

FIGS. 4a and 4b are waveform diagrams showing the arc voltage waveform at the swing end of the rotating nozzle. here,
FIG. 4a shows that the rotary nozzle 1 is close to the side wall _2L of the groove 2 on the left side when facing forward in the welding direction 5.
FIG. 4b shows the voltage waveform of the arc 4 at the swing end on the left, and on the contrary, FIG.
The voltage waveform of the arc 4 at the right swinging end where the rotating nozzle 1 extends to _R is shown, and in FIGS. 4a and 4b, the solid line is the open end of FIGS.
In the case of groove 2 of G ₀ , the dashed lines are shown in Figure 2 a and b.
The case of groove 2 with groove width G is shown.

As shown in FIG. 4a, when the rotary nozzle 1 is located at the left swing end and the arc 4 is located at the rotational position L, the arc 4 is most at the left side wall 2 _L of the groove 2. Since they are close, arc 4 at rotational position L
voltage is dropping. At this time, at the rotational position R, it is moving away from the left side wall portion _2L , so
The voltage of arc 4 does not drop. Similarly, when the rotating nozzle 1 is located at the right swing end and the arc 4 is located at the rotational position R, the voltage of the arc 4 decreases as shown in FIG. 4 voltage does not drop. The voltage of the arc 4 at these rotational positions _L and _R is higher in the wide groove 2 shown in FIG. is getting bigger.

As described above, the magnitude of the voltage drop of the arc 4 at the rotational position L at the left swinging end of the rotary nozzle 1, and the voltage of the arc 4 at the rotational position R at the right swinging end of the rotary nozzle 1. the magnitude of the decline;
Therefore, in the waveform diagrams of FIGS. 4a and 4b, in the section from the rotational position Cr of the arc 4 to Cf (the half period of rotation when the arc 4 is on the left side when facing the welding direction from the axis 1a of the rotating nozzle 1). The waveform area S _L and the waveform area S R in the section from the rotational position Cf of the arc 4 to Cr (the half period of rotation on the right side when facing the welding direction from the axis 1a of the arc 4 or the rotating nozzle ₁ ) , the difference between the waveform surfaces ΔS=|S _L −S _R | corresponds to the distance between the rotational positions L and R of the arc 4 and the side wall portions 2 _L and 2 _R of the groove 2, respectively.

Therefore, when the groove width of the groove 2 increases or decreases, the reference value of the constant waveform area is maintained without increasing or decreasing the difference ΔS in the waveform area even for the changed groove 2. For _{S 0} , _the rotating nozzle 1
If you make changes that increase or decrease the swing width of
Even for the changed groove 2, its side wall parts 2 _L and 2 _R
The materials to be welded 6 can be welded without causing welding defects.

However, in this case, the arc 4 is not necessarily located at the rotational position L when the rotating nozzle 1 is located at the left swing end, for example. Therefore, in the present invention, when the axis 1a of the rotary nozzle 1 faces forward in the welding direction, the above-mentioned The difference ΔS between the waveform areas is calculated, and the number n of times the waveform area difference ΔS exceeds a certain reference value S ₀ of the waveform area is counted. Then, the count number n is set so that the count number n falls within a predetermined range with respect to the reference value n ₀ of the constant count number, that is, a dead band width of ±△n is provided with respect to the reference value n ₀ .
The swing width of the rotating nozzle 1 is controlled by increasing or decreasing the swing width of the rotary nozzle 1 so that n ₀ −Δn<n<n ₀ +Δn.

FIG. 5 is a graph schematically showing changes in the swing width according to the above-mentioned count number. As shown by the solid line in Fig _{. 5, only the groove width can be changed to G without changing the swing width W 0 (} in the case shown in Fig. 1 a and b), which is appropriate for the groove width G 0. When increasing from ₀ to G (cases shown in FIGS. 2a and 2b), the count number n at that time decreases significantly. Therefore, as shown by the diagonal line, a dead zone width of ±△n is set for the reference value n ₀ of the count number, and as shown by the two-dot chain line, when the groove width G is wide, the count number n becomes n _0. −△n<n<n ₀ +
The swing width of the rotating nozzle 1 is set to △W so that △n
, and changes it to W ₀ +△W.

FIG. 6 is a block diagram showing the control method of the present invention. In FIG. 6, 8 is an arc voltage detector. First, the detector 8 detects the arc voltage waveform E, and the detected voltage waveform E is input to the switch 9. The switch 9 detects the arc voltage waveform E. The rotation is divided into a right half period and a left half period. switch 9
The division of the voltage waveform E is performed at the timing of a command signal based on a detection signal from the welding wire rotational position detector 10. In addition, 11 is voltage setting device 1
This is a differential amplifier for adjusting the voltage waveform E of the arc to an appropriate voltage level by using an appropriate reference voltage E ₀ set to 2.

Next, the voltage waveform E _L in the left half period of rotation and the voltage waveform E _R in the right half period of rotation obtained by the division are input to integrators 12 _L and 12 _R , respectively, and there Integrate the waveform area S _L and the waveform area S _R in the right half cycle. The waveform areas S _L and S _R obtained by integration are then input to the subtracter 13, where the difference between the waveform areas S _L and S _R is calculated, and the difference in waveform areas △S=|S Find _L −S _R |.

Next, the obtained waveform area difference ΔS is input to the comparator 14, where the waveform area setter 15 compares the waveform area reference value _S0 set in advance with the waveform area difference ΔS. . When the comparator 14 determines through comparison that the difference in waveform area ΔS exceeds the reference value S ₀ , it outputs a determination signal and inputs it to the counter 16 . The counter 16 determines that the difference ΔS in the waveform area is the reference value by inputting the determination signal.
Count the number of times n exceeding S ₀ . In this case, the counter 16 is a rotating nozzle swing position detector 17.
The count number n is determined for each left half period of the rotation of the rotating nozzle using a command signal based on a detection signal from the rotary nozzle.

Next, the count number n obtained for each of the left half period and right half period of the oscillation is input to the comparator 18, and there, the reference value n ₀ of the count number preset in the count number setting device 19 is inputted. and the above count number n. Based on the comparison, the comparator 18 outputs a swing width control signal to the swing driver 20 of the rotary nozzle so that the count number n falls within a predetermined range with respect to the reference value n ₀ . As a result, the swing width of the rotating nozzle is changed, and the swing width is controlled to correspond to the change in the groove width.

〔Effect of the invention〕

As explained above, in the present invention, when welding a workpiece while applying oscillation to a rotating nozzle, the rotating arc voltage waveform is detected and the oscillation width of the rotating nozzle is determined based on this arc voltage waveform. Since it is controlled, it is possible to easily 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]

FIG. 1a is a cross-sectional view showing a groove with a rotating nozzle whose swing width is controlled by the method of the present invention, and FIG. 1b is a cross-sectional view of the rotating nozzle in the groove of FIG. 1a. A plan view showing the locus of movement of the axial center, Fig. 2a
1 is a cross-sectional view showing a wider groove than the groove in FIG. 1a, FIG. 2b is a plan view showing the movement locus of the rotating nozzle in the groove in FIG. Rotational position diagram showing the rotational position of the arc, Figure 4a
is a waveform diagram showing the arc voltage waveform at the left swinging end of the rotating nozzle, FIG. 4b is a waveform chart showing the arc voltage waveform at the right swinging end, and FIG. FIG. 6 is a graph schematically showing changes in the swing width depending on the number of counts in the method, and is a block diagram showing the control method of the present invention. In the drawings, 1...rotating nozzle, 1a...axis center, 2...groove, 2a...swing center, _2L ...left side wall part,
2 _R ...Right side wall part, 3...Welding wire, 4...
... Arc, 5 ... Welding direction, 6 ... Material to be welded, 7
……Direction of rotation.

Claims (1)

[Claims] 1. Deriving a welding wire from a rotating nozzle facing the groove while being deviated from the axis of the rotating nozzle, supplying the welding wire together with a shielding gas into the groove, and directing the rotating nozzle toward the axis. An arc is generated between the welding wire and the groove while rotating at high speed around In a rotary arc welding method in which the rotating nozzle is moved in the welding direction of the groove while being oscillated in a period and oscillation width, thereby forming a weld bead within the groove, the voltage waveform of the arc is detecting, dividing the voltage waveform into a half period of rotation to the right and a half period of rotation to the left as the arc faces forward in the welding direction from the axis of the rotating nozzle; The waveform area of the voltage waveform in the right half cycle and the left half cycle of the rotation is determined, and the difference between the waveform areas is determined to determine whether the axis of the rotating nozzle is forward in the welding direction from the center of the oscillation. In each of the half-cycles of oscillation on the right side and the half-cycle of oscillations on the left side, count the number of times the difference in waveform area exceeds a preset reference value of waveform area, and A rotating arc characterized in that, in each half cycle, the swing width of the rotating nozzle is changed so that the count number falls within a predetermined range with respect to a preset reference value of the count number. A method for controlling the swing width of a rotating nozzle in a welding process.