JPH05318122A - Method and device for detecting end of bead - Google Patents

Abstract

PURPOSE:To secure the satisfactory welding quality of a joint part by integrating an arc voltage waveform per rotation of the arc and judging that a welding torch reaches the end of a preset bead when the variation exceeds a prescribed threshold value. CONSTITUTION:A welded joint 1 is welded through a high-speed rotary arc welding with a welding wire 3a. The arc voltage waveform or the welding current waveform of the wire 3a is integrated on the two prescribed angular areas of the arc rotational position for each rotation of the arc. The differential signal which is the difference of the integrated value is calculated for each rotation of the arc, the difference from the precalculated differential signal near the end of the preset bead 5 is integrated for each rotation of the arc, and on the judgment that, when the variation exceeds the prescribed threshold value, the welding torch 3 reaches the end of the preset bead 5, a prescribed consecutive treatment between the preset bead 5 and a newly set bead is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for detecting a bead end portion in a high speed rotary arc welding method.

[0002]

2. Description of the Related Art When welding a welded joint by a high-speed rotary arc welding method, a groove-following control method using an arc sensor is usually employed for automatically following a welding line. Here, the high-speed rotating arc welding method is a method in which the tip of the electrode wire is eccentric and the electrode nozzle of the welding torch is mechanically rotated to perform welding while rotating the arc at a high speed. Further, such a groove tracking control method is known in Japanese Patent Laid-Open No. 62-248571, and will be described with reference to FIG. 12, where an arc voltage waveform and an arc rotation position (Cf, R, Cr, L) are detected. The same phase angle φ (5 °
In the range of ≦ φ = 90 °, the arc voltage waveform is integrated (S
L, SR) and the torch position in the groove width direction (X axis) are corrected so that the difference (SL-SR) becomes zero.
In addition, in the torch height direction (Y axis), the arc 1
It is controlled so that the integral value of the welding current waveform becomes constant for each rotation. By the way, in order to ensure stable welding quality at the joint between the existing bead of the weld joint and the new bead, it is necessary to accurately detect the position of the existing bead end of the weld joint.

Conventionally, in order to connect the existing bead and the new bead, the position of the end portion of the existing bead is taught in advance, and a predetermined time is reached when the welding torch reaches the position in welding the new bead. I was carrying out the joining process.

[0004]

As described above, even if the position of the end portion of the existing bead is taught in advance, due to thermal deformation during welding and poor machining dimensional accuracy of the member, the new bead is not welded at that time. When the position is misaligned or the existing bead and the new bead are welded by different welding equipments, the teaching position and the actual end position of the existing bead 5 may be different due to the deviation of the origin position of the position detector of each welding torch. There was also a problem that it was difficult to secure the welding quality at the joint between the existing bead end of the welded joint and the new bead.

The present invention has been made to solve the above problems, and a method for detecting a bead end portion capable of stably ensuring good welding quality at a joint portion between an existing bead end of a welded joint and a new bead, and The purpose is to obtain the device.

[0006]

A bead end detecting device according to the present invention is an arc voltage detector or welding current for detecting an arc voltage or welding current between a welding torch and a workpiece to be welded by a high speed rotating arc welding method. A detector, a rotational position detector that detects the rotational angular position of the electrode nozzle, two integrators that integrate the detection signals of the arc voltage detector or the welding current detector, and two predetermined angular ranges of arc rotation. Only the timing pulse generator that outputs its drive signal based on the position detection signal of the rotational position detector so that the integrator integrates, and the deviation that is the difference between the integrated values of the detection signals integrated by the two integrators. A first differential amplifier that obtains a signal, an average value calculator that calculates the average value of the deviation signals output from the first differential amplifier, and a desired movement before the existing bead end of the welding torch. A difference output value that is the difference between the deviation signal of the first differential amplifier and the average value of the average value calculator, and a bead end detection control timing command generator that outputs a drive signal that operates the average value calculator only during separation. A second differential amplifier for obtaining the value, a multiplier for calculating the integrated value by integrating the differential output value of the second differential amplifier for each revolution of the arc from the end of the driving signal of the bead end detection control timing command generator, When the change amount of the integrated value of the unit for a predetermined number of revolutions, for a predetermined time or for a predetermined number of signals is compared with a predetermined threshold value, and when the change amount exceeds the predetermined threshold value, the welding torch is attached to the existing bead end. And a bead end determiner that outputs a bead end detection signal indicating that the bead end has been detected.

[0007]

In the present invention, the welding joint is welded by the high-speed rotating arc welding method in which the tip of the electrode nozzle of the welding torch is subjected to rotary circular motion and the arc generated at the tip of the wire is welded while rotating at high speed. The arc voltage or welding current in the inside and the arc rotation position are detected, and the arc voltage waveform or the welding current waveform is integrated for each two predetermined angular ranges of the arc rotation position for each revolution of the arc, and the difference between the integrated values. The deviation signal is calculated for each revolution of the arc, and from the time when the welding torch reaches the position where the bead end detection control is started, the deviation signal and the position where the welding torch starts the bead end detection control are within a predetermined distance. The difference from the average value of the deviation signals calculated in advance is integrated for each revolution of the arc, and the integrated value is changed for a predetermined number of revolutions, a predetermined time, or a predetermined number of signals. Amount so that the welding torch when it exceeds a predetermined threshold performs a predetermined linkage process new bead with the existing bead was determined to have reached the existing bead end.

[0008]

FIG. 1 is a block diagram showing a bead end detecting device according to an embodiment of the present invention, FIG. 2 is a block diagram showing an internal structure of a bead end judging device of the bead end detecting device, and FIG.
4 is an explanatory view showing the positional relationship between the weld joint and the electrode nozzle, FIG.
Fig. 5 is a perspective view showing a state in which welding is being performed on the weld joint with the electrode nozzle. Fig. 5 shows the rotational locus of the electrode nozzle wire and the target angle range on the Cf side and Cr side of the arc voltage integrated by the integrator. FIG. 6 is an explanatory diagram showing the principle of the bead end detecting method, and FIG. 7 is a waveform diagram showing the difference between the integrated values of the arc voltage waveforms in the two predetermined angle ranges.

In the figure, 1 is a T-shaped work which is a welded joint, 1a is a lower plate of the T-shaped work 1, 1b is a standing plate, 2 is a welding line formed by a lower plate 2a and a standing plate 1b, and 3a is Welding wire of electrode nozzle 3 and welding wire 2 of T-shaped workpiece 1
It is an existing bead installed in.

Reference numeral 10 denotes an arc voltage detector for detecting an arc voltage between the welding wire 3a of the electrode nozzle 3 and the work 1.
Reference numeral 1 is a welding current detector for detecting a welding current flowing from the welding wire 3a of the electrode nozzle 3 to the work 1, and 12 is an arc voltage detected by the arc voltage detector 10 and a welding current detector 1
A switching device for switching and outputting the welding current detected by 1; 13a, 13b are integrators provided on the output side of the switching device 12; 14 is a rotational position of an encoder or the like for detecting the rotational angle position of the welding wire 3a. A detector, 15 is an integrator 13a, 1 based on the detection signal of the rotational position detector 14.
3b is a timing pulse generator that outputs a drive signal for operating 3b.

Reference numeral 16 is a first differential amplifier for obtaining a deviation signal which is a difference between integrated values output from the two integrators 13a and 13b. Reference numeral 17 is a bead end detection control timing command generator that outputs a drive signal for a predetermined movement distance from the front of the bead end out of the previously taught movement distance from the welding start end of the welding torch 3 to the existing bead end, and 18 is the bead end detection timing. An average value calculator 19 for calculating an average value within a range of a predetermined distance from the point where the bead end detection control of the deviation signal output from the first differential amplifier 16 is started based on the drive signal of the command generator 17, A second differential amplifier that obtains a difference output value that is a difference between the deviation signal of the first differential amplifier 16 and the average value of the average value calculator 18, and 20 is the end point of the drive signal of the bead end detection control timing command generator 17. Is an integrator that calculates the integrated value by integrating the differential output value of the second differential amplifier 19 for each arc rotation.

Reference numeral 21 denotes an end detection signal indicating that the electrode nozzle 3 has reached the bead end of the T-shaped work 1 by comparing the amount of change in the integrated value of the integrator 20 per a predetermined time with a predetermined threshold value. It is a bead end determiner that outputs. This bead end determiner 21 is an average value of integrated values from the integrated value of the current value from the integrator 20 to one second before (from time T ₀ −ΔT / 2 to T _0.
An average value calculator 22 for obtaining an average value Σ) of the integrated value Σ up to + ΔT / 2, and an integrated value and an average value calculator 22 of the integrator 20
Differential amplifier 2 that calculates the difference output value that is the difference from the average value of
3, the differential output value of the differential amplifier 23 and the threshold value setter 2
5 and a comparator 24 that outputs a bead end detection signal by comparing the set threshold value.

First, the principle of the bead end detecting method will be described with reference to FIG. The welding wire 3a of the electrode nozzle 3 welds along the welding line 2 of the T-shaped work 1 while controlling the groove tracking by the arc sensor by the high-speed rotating arc welding method. At this time, the arc voltage detected by the arc voltage detector 10 changes as shown in A of FIG. 6 because the distance between the welding wire 3a and the work 1 changes according to the change of the rotational position as shown in FIG. Welding direction W
The maximum at the Cf point in front of the rotation and the Cr point at the rear in D,
It becomes minimum at point R on the standing plate side and point L on the lower plate side.

When the electrode nozzle 3 approaches the end of the existing bead 5 in the welded joint, the arc rides on the existing bead from the front Cf side of the arc rotation as shown in FIGS. 6B to 6E. The arc voltage at the rotational position on the Cf side gradually decreases, but the arc voltage at the rotational position on the Cr side does not change. Therefore, the rotating electrode nozzle 3
The arc voltage on the Cf side and the arc voltage on the Cr side are detected and the voltages of the two are compared, and it can be seen that the electrode nozzle 3 has reached the end of the existing bead 5. Therefore, the arc voltage between the Cf side and the Cr side is detected, the detected voltages are compared to obtain the difference, and the difference is compared with a threshold value set so that the bead end can be detected. That is, it is possible to perform a predetermined joining process by judging whether or not 3 has reached the end of the existing bead 5.

Next, the operation of the bead end detecting device constructed as described above will be described. First, a specific example of the high-speed rotating arc welding method in which the bead end is detected will be described. The arc rotation speed is 10 Hz or more, the arc rotation diameter D is 1 to 6 mm, and the welding speed is 10 to 300 cm.
/ Min, the welding wire diameter is 0.6 mm to 2.0 mm, and the welding current is 100 to 1000 A.

When the welding wire 3a of the electrode nozzle 3 is welding the T-shaped work 1 by the high-speed rotary arc welding method, the switch 12 is switched to, for example, the arc voltage detector 10 side, and the arc voltage detector 10 is connected. The arc voltage detected by the rotation of the electrode nozzle 3 is output to the integrators 13a and 13b. The rotation position detector 14 detects the rotation position of the rotating electrode nozzle 3 and outputs a position detection signal. Then, of the signals output from the arc voltage detector 10, for example, 315 ° to 45 ° (G as the origin, R as the origin, on the front side (hereinafter referred to as the Cf side) in the welding proceeding direction W, as shown in FIG. Angle range S _{1 of} 90 ° which is the same as the following) and an angle range S of 90 ° which is, for example, 135 ° to 225 ° on the rear side (hereinafter referred to as Cr side) in the welding proceeding direction W. _The timing pulse generator 15 outputs a drive signal to the integrators 13a and 13b based on the position detection signal of the rotational position detector 14 so that the integrators 13a and 13b operate and integrate only during the period ₂ .

The integrator 13a integrates the signal in the angle range S ₁ of 90 ° on the Cf side, and the integrator 13b integrates the signal on the Cr side at 90 ° C.
Signals in the angular range of
The integrated value of the signal integrated by a and 13b is input to the first differential amplifier 16. In this way, the integrator 13a,
What is integrated in 13b is that the arc voltage waveform has noise,
This is to prevent it from being affected.

The first differential amplifier 16 obtains the deviation signal ΔS which is the difference between the integrated value S _{1 obtained} by the integrator 13a and the integrated value S _{2 obtained} by the integrator 13b. Therefore, the deviation signal ΔS
The threshold S ₀ is compared with FIG. 7 and FIG. 9 (a that the deviation ΔS is the electrode nozzle 3 when exceeding the threshold value S ₀ came to an end portion of the T-shaped workpiece 1 existing bead 5 ) Can also be detected. In addition, L in FIG. 6 indicates a signal for bead end detection by a laser sensor prepared for confirmation of such a detection method.

However, the deviation signal .DELTA.S output from the first differential amplifier 16 is different from that of the deviation signal .DELTA.S as shown in FIG. 9 (i) due to various factors such as turbulence of the arc and fluctuations in the wire feeding speed. The waveform may be disturbed. For this reason,
Even before the bead end of the welded joint, the deviation signal ΔS exceeds the threshold value S ₀ , so that the bead end may be erroneously detected.

Therefore, in this embodiment, in order to eliminate such erroneous detection, the following signal processing is performed to detect the bead end. First, with respect to the deviation signal ΔS output from the first differential amplifier 16, the average value calculator 18 calculates the average value of the deviation signal before the bead end of the welded joint. The calculation of the average value by the average value calculator 18 is performed by operating the average value calculator 18 by the drive signal from the bead end detection control timing command generator 17.

That is, in the bead end detection timing command generator 17, for example, of the movement distance from the welding start end A to the bead end D of the welding torch 3 shown in FIG. The drive signal is output to the average value calculator 18 only during the constant movement distance l _S from the position B to the position C near the bead end of the welded joint. Therefore,
As shown in (i) of FIG. 9, the average value calculator 19 operates only during the constant moving distance l _S and calculates the average value of the deviation signal ΔS output from the first differential amplifier 16 per predetermined moving distance. Then, the average value is output to the second differential amplifier 19.

In the second differential amplifier 19, the first differential amplifier 1
The difference between the deviation signal ΔS output from 6 and the average value of the deviation signals of the average value calculator 18 is calculated, and the difference output value that is the difference is output to the integrator 20. The integrator 20 receives the drive signal of the bead end detection control timing command generator 17, integrates the difference output value of the second differential amplifier 19 for each revolution of the arc from the end of the drive signal, and calculates the integrated value. Output to the bead end determiner 21. The bead end determiner 21 obtains a change amount V of the integrated value output by the integrator 20 per predetermined time, compares the change amount V with a predetermined threshold value, and the change amount V is the predetermined threshold value. Electrode nozzle 3 is T
A bead end detection signal indicating that the end of the existing bead 5 of the character work 1 is reached is output.

The operation of the bead end discriminator 21 will be described in more detail with reference to FIG. 2. In the mean value calculator 22 in the bead end discriminator 21, the time T ₀ of the output Σ from the integrator 20.
The average value Σ from −ΔT / 2 to T ₀ + ΔT / 2 is calculated, and the average value Σ is output to the differential amplifier 23. The differential amplifier 23 calculates the difference between the integrated value Σ from the integrator 20 and the average value Σ of the average value calculation value 22 and outputs the difference signal to the comparator 24. It is an example of a method of calculating the variation amount V of the integrated value per predetermined time. {Example T ₀ = 1, Δ1 = 1 second}

The comparator 24 compares the change amount V of the integrated value output from the differential amplifier 23 per predetermined time with the predetermined threshold value set by the threshold value setting device 25, and the difference between them is a threshold value. When the value is exceeded, a bead end detection signal indicating that the electrode nozzle 3 has reached the end of the existing bead 5 of the T-shaped work 1 is output. Therefore, according to the bead end detection signal output from the comparator 24, the electrode nozzle 3 causes the existing bead 5 to move.
It is possible to detect with high accuracy that the end of the is reached. The threshold value set by the threshold value setter 24 is set to a value indicating that the change amount V of the integrated value Σ of the integrator 20 has sharply increased and reached the end position, and the comparator 24 sets the change amount. The bead end is judged at the moment when V exceeds the threshold value.

In this way, the average value calculator 18 calculates the average value from the deviation signal ΔS output from the first differential amplifier 16, and the second differential amplifier 19 calculates the difference between the deviation signal and the average value. The difference is added by the integrator 20 because the first reference integrated value to be integrated with the integrated value 20 is set to zero level so that the change in the deviation signal can be grasped as a sharp change. It is designed so as not to be affected by the disturbance of the waveform of the deviation signal caused by various factors such as the fluctuation of the wire feeding speed and the wire feeding speed.

Further, the integrated value of the integrator 20 is not immediately compared with the threshold value to detect the bead end, but the change amount of the integrated value per predetermined time is compared with the threshold value to detect the bead end. The reason is that the integrated value at the end of the existing bead suddenly increases during integration, so the sudden change point (inflection point) of the integrated value
This is because the bead end position can be detected more reliably and highly accurately by determining the bead end by finding Therefore, good welding quality between the existing bead end of the welded joint and the new bead can be stably ensured.
Although the amount of change in the integrated value is captured as the amount of change per predetermined time in the embodiment, the bead end can be detected by capturing the amount of change in the integrated value per predetermined rotation speed or the predetermined number of signals. Of course.

In the embodiment shown in FIG. 5, the integrator 13 is used.
The target of the arc voltage integrated by a and 13b is 3 on the Cf side.
An angle range S _{1 of} 90 °, which is 15 ° to 45 °, and Cr
On the side, the angle range S _{2 of} 90 °, which is 135 ° to 225 °
However, it goes without saying that the angle range is not limited to 90 °, and the bead end can be detected if it is 5 ° or more and 180 ° or less.

Further, in the above-mentioned embodiment, the arc voltage detector 10 detects the arc voltage, and the signal processing is performed to detect the bead end of the welded joint.
Welding current detector 1 by switching 2 to welding current detector 11 side
The bead end of the welded joint can be detected by performing signal processing on the welding current detected by No. 1 as in the above-described embodiment. The arc voltage decreases the voltage at the Cf position, while the welding current reversely decreases the Cr voltage.
The only difference is that the current at the R position on the side increases.

[0029]

As described above, the present invention detects the arc voltage or welding current during welding and the rotating position of the arc when the workpiece is welded by the high-speed rotating arc welding method, and the arc is detected. The arc voltage waveform or the welding current waveform is integrated with respect to each of the two predetermined angular ranges of the arc rotation position for each revolution of the arc, and the deviation signal, which is the difference between the integrated values, is calculated for each revolution of the arc. From the time when it reaches the position to start the detection control, the difference between the deviation signal and the average value of the deviation signal calculated in advance within a predetermined distance from the position where the welding torch starts the bead end detection control makes one arc revolution. It is determined that the welding torch has reached the existing bead end when the variation of the accumulated value for a predetermined number of revolutions, a predetermined time or a predetermined number of signals exceeds a predetermined threshold value. The welding arc itself functions as a sensor because it performs a predetermined joining process between the cord and the new bead, and it is not affected by deformation such as thermal strain or shrinkage due to welding or bending of the wire. Even if the arc voltage waveform or the welding current waveform itself is disturbed due to various factors such as turbulence or fluctuations in the wire feed speed, the signal processing is performed so that it is not easily affected by the turbulence of the waveform, so the bead end is erroneously detected. Without this, there is an effect that the bead end position of the welded joint can be detected reliably and highly accurately in the welding process, and good welding quality of the existing bead, the new bead and the bead joint portion of the welded joint can be stably ensured.

[Brief description of drawings]

FIG. 1 is a block diagram showing a bead end detecting device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an internal configuration of an inflection point determining device of the bead end detecting device.

FIG. 3 is an explanatory diagram showing a relationship between a welded joint and an electrode nozzle.

FIG. 4 is a perspective view showing a state where welding is being performed on a weld joint by an electrode nozzle.

FIG. 5 is an explanatory view showing a mode of a target angle range on a Cf side and a Cr side of an arc voltage integrated by an integrator with a rotation trajectory of a wire of an electrode nozzle.

FIG. 6 is an explanatory diagram showing the principle of a method for detecting a bead end portion.

FIG. 7 is a waveform diagram of a signal showing a difference between integrated values of arc voltage waveforms in two predetermined angle ranges.

FIG. 8 is an explanatory diagram showing a detection procedure of a bead end detection device for a welded joint.

FIG. 9 is a waveform diagram showing a signal waveform at each part of the bead end detection device.

FIG. 10 is an explanatory diagram showing a groove tracking control method using a conventional arc sensor.

Claims (2)

[Claims] 1. A high-speed rotating arc welding method, in which a rotating circular motion is applied to a tip of an electrode nozzle of a welding torch to perform welding while rotating an arc generated at a tip of a wire at a high speed. The rotation position is detected, and the arc voltage waveform or the welding current waveform is integrated for two predetermined angular ranges of the arc rotation position for each revolution of the arc, and the deviation signal which is the difference between the integrated values is calculated for each revolution of the arc. From the time when the welding torch reaches the position to start the bead end detection control after the calculation, the deviation signal and the average of the deviation signal calculated in advance within a predetermined distance from the position where the welding torch starts the bead end detection control The difference from the value is integrated for each revolution of the arc, and welding is performed when the amount of change of the integrated value for a predetermined number of revolutions, a predetermined time or a predetermined number of signals exceeds a predetermined threshold value. Detection method of bead end over switch is characterized in that as it is determined to have reached the existing bead end performs predetermined boundary processing the existing bead with new beads. 2. An arc voltage detector or a welding current detector for detecting an arc voltage or a welding current between a welding torch and a workpiece to be welded by a high speed rotary arc welding method, and a rotational position detection for detecting a rotational angle position of an electrode nozzle. Position detector, two integrators for integrating detection signals of the arc voltage detector or the welding current detector, and rotational position detection of the drive signal so that the integrator integrates only in two predetermined angular ranges of rotation of the arc. From a timing pulse generator that outputs based on a position detection signal of a detector, a first differential amplifier that obtains a deviation signal that is a difference between integrated values of detection signals integrated by two integrators, and a first differential amplifier It outputs an average value calculator that calculates the average value of the output deviation signal and a drive signal that operates the average value calculator only during the desired movement distance before the existing bead end of the welding torch. Bead end detection control timing command generator, a second differential amplifier that obtains a difference output value that is the difference between the deviation signal of the first differential amplifier and the average value of the average value calculator, and bead end detection control timing command An integrator that integrates the second differential amplifier difference output value for each arc revolution from the end of the drive signal of the generator to calculate the integrated value, and a predetermined number of revolutions, a predetermined time or a predetermined number of signals of the integrated value of the integrator. A bead end determiner that compares the amount of change in hits with a predetermined threshold value and outputs a bead end detection signal indicating that the welding torch has reached the existing bead end when the amount of change exceeds a predetermined threshold value. And a bead end detecting device.