JPH0671665B2 - How to detect temporary beads - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a temporary bead detection method in high-speed rotating arc welding when the electrode rotation center is not in the groove route, such as tandem welding and unequal leg 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]

Temporary bead that exists at any position on the weld line such as fillet welded joints not only adversely affects the penetration depth of the main welding, bead shape and leg length, etc. However, there is a problem in that there is a possibility that the contact control may be disturbed and the control of the groove tracking by other contact sensors may also be disturbed.

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

[Means for solving problems]

In high-speed rotating arc welding performed by shifting the axis of rotation of the rotating electrode from the groove route, (a) detecting the arc voltage waveform or welding current waveform of the rotating electrode, and (b) determining the arc voltage waveform or welding current waveform as the welding progress direction. C. The arc voltage waveform or welding current waveform divided above is divided into the left and right sides with reference to the right side point R on the right side of 90 degrees toward the welding advancing direction and the left point L on the left side of 90 degrees toward the welding advancing direction. were calculated area to make a constant angle, it calculates the difference between reference two the right point R was the area S _R and the reference to the left point L was the area S _L (S _R -S _L), e the difference The difference ΔS between the change in (S _R −S _L ) and a predetermined reference value is calculated, and the temporary bead is detected by the value of the difference ΔS.

[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 is a perspective view showing an embodiment of the present invention.
The case of performing fillet welding with a long leg using electrodes is shown. In the figure, 1 is a lower plate, 2 is a standing plate standing on the lower plate 1, 3 is a groove route, 4 is a leading electrode arranged with the axis of rotation toward the lower plate 1 side from the groove route 3, and 5 is A rotating motor in which the leading electrode 4 rotates in the direction of the arrow 6, 7 is a trailing electrode arranged with the rotation axis line from the groove route 3 toward the standing plate 2, and 8 is a trailing electrode 7
A rotating motor for rotating the wire; 9 is a wire passing through the eccentric holes of the current-carrying chips provided at the tips of the leading electrode 4 and the trailing electrode 7; 10 is an arc; 11 is a leading bead formed by the leading electrode 4; Is a trailing bead formed by the trailing electrode 7. The distance between the leading electrode 4 and the trailing electrode 7 is set so that the leading molten pool formed by the leading electrode 4 and the trailing molten pool formed by the trailing electrode 7 do not overlap each other to prevent magnetic blowing and to form a bead shape. Do not disturb.

FIG. 2 is a side view of the leading electrode 4 configured as described above. In FIG. 2, the welding direction is perpendicular to the paper surface and is the direction from the back surface of the paper surface to the front surface, la is the arc length, le is the wire protrusion length, and Ex is the distance between the electrode and the base metal.

FIG. 3 is a view of the preceding electrode (hereinafter referred to as an electrode) 4 shown in FIG. 2 as seen from the rotation axis direction. In FIG. 3, Cf, Cr, R and L are generated by rotating the electrode 4. The position of the wire 9 when it is moving, Cf is the position of the wire 9 ahead of the welding direction indicated by the arrow 13, R is the position of the wire 9 on the right side of 90 degrees toward the welding direction 13, and L is the direction of welding The position of the wire 9 on the left side of 90 degrees, Cr is the wire 9 behind the welding direction 13.
Indicates the position of. Further, φ represents a rotation angle of the wire 9 with respect to the welding direction 13.

As shown in FIGS. 2 and 3, when the electrode 4 is rotated under a constant wire feeding speed, the arc length la varies depending on the position of the wire 9 during rotation, and the distance Ex between the electrode 4 and the base material Ex Changes. When the distance Ex changes, the load characteristics also change, and the welding current I and the voltage (hereinafter, referred to as arc voltage) E between the electrode 4 and the base metal change. The change in the welding current I or the arc voltage E due to the change in the distance Ex changes linearly with the distance Ex unless the change in the distance Ex is large. As shown in FIG. 2, when there is no temporary bead on the groove route 3, when the electrode 4 rotates, the distance Ex changes according to the position of the wire 9 with a sine wave as the basic shape. E also changes in a sine wave shape corresponding to the position of the wire 9. In addition,
This relationship holds true not only for consumable electrodes but also for non-consumable electrodes.

FIG. 4 shows the waveform of the arc voltage E which changes according to the position of the rotating wire 9 or arc when there is no temporary bead on the groove route 3, and FIG. 5 changes according to the position of the arc. The waveform of the welding current I is shown. The arc voltage waveform and the welding current waveform shown in FIGS. 4 and 5 are vertically inverted, and the welding current waveform shown in FIG. 5 can be obtained only with a welding power source having a constant voltage characteristic. The arc voltage waveforms shown in the figure can be obtained with both constant voltage and constant current welding power sources.

As shown in FIGS. 4 and 5, when there is no temporary bead on the groove route 3, the arc voltage waveform or the welding current waveform becomes a symmetrical waveform for each cycle, and the right side point R of the arc
The difference S ₀ = (S _R -S _L ) between the area S _{R of the} waveform made at a constant angle φ ₀ with reference to the area S _L made at the constant angle φ ₀ with reference to the left point L of the arc is the welding condition etc. It is a constant value determined by.

However, when the rotating arc rides on the temporary bead 14 as shown in FIG. 6, the arc length la becomes short at the position of the wire 9 centered on the right side point R in the welding proceeding direction. The arc voltage waveform has an arc voltage waveform in which the voltage level is locally reduced around the right side point R as shown in FIG. Therefore, the right side point R of this arc voltage waveform
The difference between the area S _L relative to the surface area S _R and the left point L relative to the becomes smaller than the difference between S ₀ of the area when temporarily attached beads 14 are not present.

Therefore, the temporary bead can be detected by detecting the change in ΔS represented by the following formula ΔS = (S _R −S _L ) −S ₀ (1). FIG. 8 shows the relationship between ΔS and the welding time T. In FIG. 8, T ₁ is the time when the arc rides on the temporary bead 14, and T ₂ is the arc temporary bead.
Indicates the time at the moment of departure from 14. As shown in FIG. 8, ΔS becomes zero when the temporary bead 14 does not exist, but the level of ΔS decreases when the temporary bead 14 is arced. Therefore, the dead zone S _{1 with a} certain level of ΔS
The presence of the temporary bead 14 can be detected by detecting the time when the time exceeds. Further, the size of ΔS that changes due to the existence of the temporary bead 14 has a good correlation with the size of the temporary bead. Therefore, the size of the temporary bead 14 can also be detected by detecting the size of ΔS that changes.

When the temporary bead is detected, the range of the constant angle φ ₀ is within the range of ± 2.5 degrees to ± 90 degrees with reference to the right side point R and the left side point L. The lower limit of the constant angle φ ₀ is set to ± 2.5 degrees in order to eliminate the influence of the noise component on the waveform generated when the angle is less than ± 2.5 degrees.

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

First, the arc voltage E is detected by the arc voltage detector 40, and the detected arc voltage E is divided by the switch 41 into the right side point R side and the left side point L side in the welding advancing direction. The timing of division of the arc voltage E by the switch 41 is determined by a command signal from the switching logic circuit 42. In the switching logic circuit 42, the rotation angle φ of the wire 9 detected by the rotation position detector 43 is set to φ ₀ .
It is detected that the wire 9 is within a constant angle φ ₀ set in advance, and the voltage waveform when the wire 9 is within the constant angle φ ₀ with reference to the right side point R is output from the switch 41 to the right integrator 44. . Similarly, the voltage waveform when it is within a constant angle φ ₀ with reference to the left side point L of the wire 9 is output from the switch 41 to the left integrator 45, and the voltage waveforms are integrated by the respective integrators 44, 45.
The n setter 46 is set with the number of times n of these integration processes, and the integrators 44 and 45 perform waveform integration with respect to n times of arc rotations output via the switching logic circuit 42. , Its outputs S _R and S _L are stored in the right side memory 47 and the left side memory 48, respectively. Each memory 47, 48 outputs the signal S _R and the signal S _L to the differential amplifier 49 while repeatedly storing and holding the signals S _R , S _L input from the integrators 44, 45 every n times. The differential amplifier 49 calculates the difference (S _R -S _L ) between the signal S _R and the signal S _L and outputs it to the differential amplifier 50 at the next stage. The differential amplifier 50 receives the difference signal (S _R -S _L ) and the reference value S ₀ when the temporary bead previously set in the reference voltage setting device 51 does not exist.
The difference ΔS = (S _R −S _L ) −S ₀ is calculated and output to the temporary bead determining circuit 52. The difference signal .DELTA.S input to the temporary bead determining circuit 52 becomes zero level when there is no temporary bead as shown in FIG. 8, and the level of the difference signal .DELTA.S decreases when the temporary bead exists. . This decrease in the level of the difference signal ΔS is caused by the dead band set in the dead band setting unit 53 in advance.
When the level of S ₁ is exceeded, the temporary bead determining circuit 52 detects the presence of the temporary bead.

Further, after the existence of the temporary bead is detected by the temporary bead determining circuit 52, the size of the temporary bead is detected according to the signal level of the difference signal ΔS.

When the presence and size of the temporary bead are detected by the temporary bead determining circuit 52 as described above, the welding condition is adaptively controlled according to the determination 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.

Further, in the above embodiment, the constant angle φ ₀ is set around the right side point R and the left side point L of the welding advancing direction. Even if the fixed angle φ ₀ is set only in the rearward direction, the temporary bead can be detected as in the above embodiment.

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. Even if is not on the groove route, the temporary bead on the welding line can be detected in a non-contact and real-time manner, and the optimum control can be performed.

[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
FIG. 7 is a side view of a welded portion when a temporary bead is present in a groove route, FIG. 7 is an arc voltage waveform diagram when a temporary bead is present, and FIG. 8 is a temporary bead discrimination in the above embodiment. The waveform diagram and FIG. 9 are block diagrams of the control circuit of the above embodiment. 1 ... Lower plate, 2 ... Standing plate, 3 ... Route of groove, 4 ...
Leading electrode, 7 ... Trailing electrode, 9 ... Wire, 14 ... Temporary bead.

Claims (1)

[Claims] 1. In high-speed rotary arc welding performed by shifting the axis of rotation of a rotating electrode from the groove route, (a) detecting the arc voltage waveform or welding current waveform of the rotating electrode, and (b) the arc voltage waveform or welding current. The waveform is divided into left and right sides based on the welding progress direction, and the arc voltage waveform or welding current waveform obtained above is divided by 90 degrees on the right side of the welding progress direction and point R on the right side of the welding progress direction and 90 degrees on the left side of the welding progress direction. calculates the area to make a constant angle relative to the point L, calculates a difference between the reference to two the right point R was the area S _R and the reference to the left point L was the area S _L (S _R -S _L) E. The difference ΔS between the change in the difference (S _R -S _L ) and the predetermined reference value is calculated, and the temporary bead is detected by the value of the difference ΔS. Detection method for temporary beads.