JPH0671666B2 - How to detect temporary beads - Google Patents

Description

The present invention relates to a temporary bead detection method in high-speed rotary arc welding.

[Conventional technology]

Conventionally, for example, when performing fillet welding or the like, temporary welding is performed to temporarily fix the groove portion, and main welding is performed after temporary mounting.

[Problems to be solved by the invention]

The temporary bead existing at an arbitrary position on the weld line of the fillet welded joint or the like adversely affects the penetration depth of the main welding, the bead shape and the leg length. Further, there is a problem that the groove profile may be disturbed not only in the groove profile control by the arc sensor but also in the groove profile control by other contact sensors.

The present invention has been made to solve the above problems, and proposes a temporary bead detection method capable of detecting the existence and size of a temporary bead in real time in a non-contact manner in high-speed rotary arc welding. That is the purpose.

[Means for solving problems]

The temporary bead detection method according to the present invention, in high-speed rotating arc welding performed by rotating the electrode while rotating the arc at high speed, (a) detecting the arc voltage waveform or welding current waveform of the rotating electrode, and The waveform or welding current waveform is centered on the front point Cf of the welding advancing direction, the right side point R of 90 degrees to the welding advancing direction, the rear point Cr of the welding advancing direction, and the left point L of 90 degrees to the welding advancing direction. Fixed angle of ± 45 degrees or less ± φ
Divide by ₀ , and calculate the area Scf, S _R , Scr, S _L created by the arc voltage waveform or welding current waveform divided around the front point Cf, the right side point R, the rear side point Cr and the left side point L. , with a focus on the area S _R and the left point L around the sum Scf + Scr and right points R of the area Scr centered around and was the area Scf and rear point two front point Cf of the area S _L Sum S _R
+ S _L is calculated respectively, and the change in the difference between the sum of the above areas Scf + Scr and the sum of the areas S _R + S _L is calculated, and the change in the above difference is compared with a predetermined reference value.
It is characterized in that it is judged that the welding arc is on the temporary bead by judging that the change in the difference exceeds the reference value.

[Action]

In the present invention, the temporary bead is detected based on the fluctuation of the voltage waveform or the welding current waveform of the rotating arc, so that the temporary bead on the welding line can be detected in non-contact and in real time.

〔Example〕

FIG. 1 shows a fillet welded joint to be welded according to an embodiment of the present invention, in which 1 is a lower plate, 2 is a standing plate standing on the lower plate, and 3 is a temporary bead existing on a groove route 4. Is.

With the joint formed as described above, as shown in FIG. 2, the electrode 5 is rotated in the direction of arrow 7 by a rotation motor (not shown) at a rotation speed adapted to the welding conditions, and the arc at the tip of the wire is rotated at high speed. Welding is performed along the groove route 4. In FIG. 2, la is the arc length.

FIG. 3 is a view of the electrode 5 shown in FIG. 2 as viewed from the direction of the rotation axis. In the figure, Cf, Cr, R, L indicate the positions when the electrode 5 is rotating, and Cf is the welding direction. 8 is the position of the electrode 5 in front, R is the position of the electrode 5 on the right side of 90 degrees toward the welding direction 8,
L indicates the position of the electrode 5 on the left side of 90 degrees, and Cr indicates the position of the electrode 5 behind the welding direction 8. Further, φ represents the rotation angle of the electrode 5 with respect to the welding direction 8.

FIG. 4 shows a waveform of the arc voltage E which changes corresponding to the position of the rotating electrode 5, that is, the arc when there is no temporary bead 3 on the groove route 4, and FIG. 5 corresponds to the position of the arc. 3 shows the waveform of the welding current I that changes with time. 4 and 5
The waveform of the arc voltage E and the waveform of the welding current I shown in the figure are vertically inverted. The welding current I shown in FIG.
The waveform of can be obtained only with a welding power source having a constant voltage characteristic, but the waveform of the arc voltage E shown in FIG.
It can be obtained with any welding power source having a constant current characteristic.

As shown in FIGS. 4 and 5, when there is no temporary bead 3 on the groove route 4, the arc voltage waveform or the welding current waveform becomes the same waveform for each cycle, and the arc forward point Cf is centered. Area Scf and backward point C made at a constant angle ± φ ₀ of ± 45 degrees or less
Sum of area Scr made at a constant angle ± φ ₀ centered on r Scf + Scr
And the area created at a constant angle ± φ ₀ centered on the right side of the arc
The sum of the areas S _L to make about the S _R and the left point at an angle ± phi ₀
The difference from S _R + S _L , S ₀ = (Scf + Scr) − (S _R + S _L ) is a constant value.

While the electrode nozzle 5 is rotating, the arc is rotated to perform fillet welding, and at the moment the rotating arc rides on the temporary bead 3, first, the arc length la of the front point Cf in the welding proceeding direction becomes short. The arc voltage waveform shown in FIG. 4 has an arc voltage waveform in which the voltage level is locally reduced at the front point Cf as shown in FIG. 6 (a). Therefore, the sum Scf + Scr of the area Scf centered on the front point Cf and the area Scr centered on the rear point Cr of this arc voltage waveform and the sum S _R + S _{L of} the areas centered on the right side point R and the left side point _L. Difference with (Scf + Scr)-(S _R +
S _L ) is smaller than the above constant value S ₀ . When the welding progresses and the rear point Cr rides on the temporary bead 3, the arc voltage waveform has a voltage level lower at the rear point Cr as shown in FIG. 6 (b), and S ₀ > (Scf + Scr) The relationship of − (S _R + S _L ) is maintained as it is.

The welding progresses further and the front point Cf of the arc is the temporary bead 3
As shown in FIG. 6 (c), the voltage level of the arc voltage waveform rises at the front point Cf, but the voltage level of the rear point Cr decreases, and the arc of the rear point Cr is temporarily attached to the bead. until outside the _{3 S 0> (Scf + Scr} ) - have summer and (S _R + S _L).

The While connexion formula △ S = {(Scf + Scr ) - (S R + S L)} - S 0 ...... by detecting a change in the shown △ S in (1) can be detected temporarily attached bead. FIG. 7 shows the relationship between the ΔS and the welding time T. In FIG. 8, T ₁ is the forward point Cf of the arc.
Is on the temporary bead, T ₂ is the rear point of the arc Cr is on the temporary bead, T ₃ is the front point of the arc Cf is off the temporary bead, T ₄ is the rear point of the arc Indicates when Cr is off the temporary bead. As shown in FIG. 7, ΔS is zero when there is no temporary bead, but the level of ΔS decreases when the temporary bead is arced. Therefore, the presence of the temporary bead can be detected by detecting when the decrease in the level of ΔS exceeds the certain level of the dead zone S ₁ . Further, the size of ΔS that changes due to the existence of the temporary bead has a good correlation with the size of the temporary bead. Therefore, the size of the temporary bead can be detected by detecting the size of ΔS that changes.

When detecting the temporary bead, the range of the constant angle φ ₀ is 45 degrees or less. The upper limit of the constant angle φ ₀ is set to 45 degrees in order to avoid overlapping of areas.

The temporary bead detection method will be described with reference to the block diagram of the control circuit shown in FIG.

First, the voltage detector 40 detects the arc voltage E, and the switch 41 divides the detected arc voltage E into the front point Cf side, the rear point Cr side, the right side point R side, and the left side point L side in the welding direction. Switch
The timing of division of the arc voltage E by 41 is controlled by a command signal from the switching logic circuit 42. The switching logic circuit 42 detects the rotation angle φ of the wire 6 detected by the rotation position detector 43 and a predetermined angle φ ₀ within a predetermined range of 45 degrees or less.
Is compared with the output of the φ ₀ setting device 44, and the waveform of the section in which the rotation angle of the wire 6 is ± φ ₀ centering on the front point Cf is output from the switch 41 to the front integrator 45. Similarly, the waveform of the section in which the rotation angle of the wire 6 is ± φ ₀ centering on the rear point Cr, the right side point R and the left side point L is output from the switch 41 to the rear integrator 46, the right integrator 47 and the left integrator, respectively. It is output to 48, and each waveform is integrated by each integrator 45-48. The number of times n of integration processing is set in the n setter 49, and each of the integrators 45 to 48 performs waveform integration for n rotations of the arc output via the switching logic circuit 42. , Outputs Scf, Scr, S _R and S _L are stored in the front storage device 50, the rear storage device 51, the right storage device 52 and the left storage device 53, respectively.
Each storage 50-53 is a signal Scf input from the integrator 45 to 48 every n times, Scr, and outputs a signal Scf and Scr while repeating memory retention of S _R and S _L to the adder 54, the signal S Add _R and S _L 55
Output to. Output to the differential amplifier 56 calculates the sum Scf + Scr adder 54 the signal Scf and Scr, signals in the other adder 55 S _R
And the sum of S _L and S _R + S _L are calculated and output to the differential amplifier 56 as well.
In the differential amplifier 56, the difference (Scf + Scr) − (S _R + S _L ) between the sum Scf + Scr and S _R + S _L of the above signals is calculated, and the differential amplifier 57 in the next stage
Output to. The differential amplifier 57 uses the difference signal (Scf + Scr) −
The difference between the value S ₀ of _{(S R + S L) -} (S R + S L) and, previously determined reference voltage when temporarily attached beads that had been set in the setting unit 58 does not exist above difference signal (Scf + Scr) ΔS = {(Scf + Scr) − (S _R + S _L )} − S ₀ is calculated and output to the temporary bead determining circuit 59. The difference signal ΔS input to the temporary bead discriminating circuit 59 becomes zero level when there is no temporary bead as shown in FIG. When the rotating arc rides on the temporary bead, the level of the difference signal ΔS decreases. Therefore, in the temporary bead determination circuit 59, the signal level of the difference signal ΔS and the dead zone S ₁ previously set in the dead zone setter 60 are set. And the presence of the temporary bead is detected by detecting when the signal level of the difference signal ΔS exceeds the dead zone S ₁ . Further, after the presence of the temporary bead is detected by the temporary bead determination circuit 59, the size of the temporary bead is detected according to the position of the signal level of the difference signal ΔS.

When the presence and size of the temporary bead are detected by the temporary bead discriminating circuit 59 as described above, the groove automatic control method is stopped or changed and the welding condition is adaptively controlled according to the discrimination signal. .

Although the temporary bead is detected by detecting the arc voltage waveform in the above embodiment, the temporary bead can be detected in the same manner as in the above embodiment by detecting the welding current waveform shown in FIG.

Furthermore, although the above embodiment describes fillet welding, it can be similarly applied to butt welding or narrow groove welding.

〔The invention's effect〕

As described above, the present invention can detect the presence and size of the temporary bead based on the fluctuation of the voltage waveform or the welding current waveform of the rotating arc. It is possible to detect attached beads and perform adaptive control.

[Brief description of drawings]

1 is a perspective view of a fillet welded joint to be welded according to an embodiment of the present invention, FIG. 2 is a side view of a welded portion of an embodiment of the present invention,
FIG. 3 is an explanatory view showing wire positions in the above embodiment, and FIG.
Figure is arc voltage waveform diagram, Fig. 5 is welding current waveform diagram, 6th
Figures (a), (b), and (c) are arc voltage waveform diagrams in which a rotating arc rides on a temporary bead,
FIG. 7 is a waveform diagram for determining the temporary bead in the above embodiment, and FIG. 8 is a block diagram of the control circuit in the above embodiment. 1 ... Lower plate, 2 ... Standing plate, 3 ... Temporary bead, 4 ... Route of groove, 5 ... Electrode, 6 ... Arc.

Claims (1)

[Claims] 1. In high-speed rotating arc welding in which an arc is rotated at a high speed by rotating an electrode, (a) the arc voltage waveform or welding current waveform of the rotating electrode is detected, and (b) the arc voltage waveform or welding current waveform. Is the forward point Cf in the welding direction, the right point R is 90 degrees to the welding direction,
A fixed angle of ± 45 degrees or less centered on the rear point Cr in the welding progress direction and the left point L on the left side of 90 degrees toward the welding progress direction ±
Divide by φ ₀ and calculate the area Scf, S _R , Scr, S _L created by the arc voltage waveform or welding current waveform divided around the front point Cf, the right side point R, the rear side point Cr and the left side point L. Then, the sum Scf + Scr of the area Scf centered on the front point Cf and the area Scr centered on the rear point and the area S _R centered on the right side point R and the area S L centered on the left side point _L Sum of
S _R + S _L are calculated respectively, and the change in the difference between the area sum Scf + Scr and the area sum S _R + S _L is calculated, and the change in the difference is compared with a predetermined reference value. A method for detecting a temporary bead, comprising determining that the welding arc is on the temporary bead when the change exceeds a reference value.