JP2616633B2 - Bead edge detection method and device - Google Patents

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 in a high-speed rotary arc welding method.

[0002]

2. Description of the Related Art When welding is performed on a weld joint by a high-speed rotating arc welding method, a groove tracking 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 an electrode wire is eccentric, and welding is performed while rotating the arc at a high speed by mechanically rotating an electrode nozzle of a welding torch. Such a groove following control method is known in Japanese Patent Application Laid-Open No. 62-248571 and the like. Referring to FIG. 12, an arc voltage waveform and an arc rotation position (Cf, R, Cr, L) are detected. And 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) is corrected so that the difference (SL-SR) becomes zero.
In the torch height direction (Y axis), the arc 1
Control is performed so that the integral value of the welding current waveform is constant at each rotation. By the way, it is necessary to accurately detect the existing bead end position of the welded joint in order to stably secure the quality of welding at the joint between the existing bead of the welded joint and the new bead.

[0003] Conventionally, in order to perform a joining process between an existing bead and a new bead, the position of the end of the existing bead is taught in advance, and a predetermined time is reached when the welding torch reaches that position in welding the new bead. Connection processing was performed.

[0004]

As described above, even if the position of the end of the existing bead is taught in advance, the position of the existing bead may be lost when welding a new bead due to thermal deformation during welding and poor processing dimensional accuracy of the member. When the position is shifted or when the existing bead and the new bead are welded by different welding devices, the teaching position and the actual end position of the existing bead 5 are determined by the deviation of the origin position of the position detector of each welding torch. In addition, there has been a problem that it is difficult to ensure welding quality at a joint between an existing bead end of a welded joint and a new bead.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a method for detecting a bead end which can stably secure good welding quality at a joint between an existing bead end and a new bead of a welded joint. The aim is to obtain a device.

[0006]

An apparatus for detecting a bead end according to the present invention comprises an arc voltage detector or a welding current for detecting an arc voltage or a welding current between a welding torch and a workpiece to be welded by a high-speed rotating arc welding method. A detector, a rotation position detector for detecting a rotation angle position of the electrode nozzle, two integrators for integrating detection signals of the arc voltage detector or the welding current detector, and two predetermined angle ranges of arc rotation. A timing pulse generator that outputs a drive signal based on the position detection signal of the rotational position detector so that the integrator only integrates, and a deviation that is a difference between the integrated values of the detection signals integrated by the two integrators. A first differential amplifier for obtaining a signal, an average calculator for calculating an average value of the deviation signal output from the first differential amplifier, and a desired movement of the welding torch just before the existing bead end. A bead end detection control timing command generator that outputs a drive signal for operating the average calculator only during the separation, and a difference output value that is a difference between the deviation signal of the first differential amplifier and the average of the average calculator. A second differential amplifier that calculates the differential output value of the bead end detection control timing command generator, and an integrator that integrates the differential output value of the second differential amplifier for each arc rotation to calculate an integrated value. The amount of change per unit number of revolutions, a predetermined time, or a predetermined number of signals of the vessel is compared with a predetermined threshold value, and when the change amount exceeds a predetermined threshold value, the welding torch is moved to the end of the existing bead. And a bead end determiner for outputting a bead end detection signal indicating that the bead has come.

[0007]

According to the present invention, welding is performed on a welded joint by a high-speed rotating arc welding method in which a rotating circular motion is applied to the tip of an electrode nozzle of a welding torch and an arc generated at the wire tip is rotated at a high speed to perform welding. The arc voltage or welding current in the arc is detected for two predetermined angular ranges of the arc rotation position for each rotation of the arc, and the difference between the integrated values is detected. The deviation signal is calculated for each rotation of the arc, and the deviation signal and the position where the welding torch starts the bead end detection control are within a predetermined distance before the welding torch reaches the position where the bead end detection control is started. The difference between the previously calculated deviation signal and the average value is integrated for each rotation of the arc, and the integrated value is changed for a predetermined number of rotations, 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 configuration of a bead end judging device of the bead end detecting device.
FIG. 4 is an explanatory view showing a positional relationship between a weld joint and an electrode nozzle, and FIG.
FIG. 5 is a perspective view showing a state in which welding is performed on the welded joint by the electrode nozzle, and FIG. 5 is a view showing a rotation locus of the wire of the electrode nozzle and a target angle range of the Cf side and the Cr side of the arc voltage integrated by the integrator. FIG. 6 is an explanatory diagram showing the principle of a method of detecting a bead end, and FIG. 7 is a waveform diagram showing a difference between integral values of arc voltage waveforms in two predetermined angle ranges.

In the figure, 1 is a T-shaped work which is a welding joint, 1a is a lower plate of a 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, 3a is a welding line. Welding wire for electrode nozzle 3, welding wire 2 for T-shaped work 1
It is an existing bead provided in.

An arc voltage detector 10 detects an arc voltage between the welding wire 3a of the electrode nozzle 3 and the workpiece 1.
Reference numeral 1 denotes 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 denotes an arc voltage detected by the arc voltage detector 10 and the welding current detector 1.
Switchers for switching the welding current detected by 1 to output the same, 13a and 13b are integrators respectively provided on the output side of the switcher 12, and 14 is a rotational position of an encoder or the like for detecting a rotational angle position of the welding wire 3a. The detector 15 is provided with an integrator 13a, 1 based on a 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 denotes a first differential amplifier for obtaining a deviation signal which is a difference between the integrated values output from the two integrators 13a and 13b. Reference numeral 17 denotes a bead end detection control timing command generator for outputting a drive signal for a fixed movement distance from just before the bead end of a pre-taught movement distance from the welding start end of the welding torch 3 to the existing bead end, and 18 is a bead end detection timing. An average calculator 19 for calculating an average of a deviation signal output from the first differential amplifier 16 based on a drive signal of the command generator 17 within a predetermined distance from a point where bead end detection control is started; A second differential amplifier 20 for obtaining a difference output value which is a difference between the deviation signal of the first differential amplifier 16 and the average value of the average value calculator 18. From the second differential amplifier 19 for each rotation of the arc to calculate an integrated value.

Numeral 21 compares an amount of change in the integrated value of the integrator 20 per predetermined time with a predetermined threshold value, and generates an end detection signal indicating that the electrode nozzle 3 has come to the bead end of the T-shaped work 1. It is a bead end determiner that outputs. The bead end determiner 21 calculates the average value of the integrated value 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 calculator 22 for calculating the average value of the integrated value Σ) up to + ΔT / 2, and an integrated value and average calculator 22 of the integrator 20
Differential amplifier 2 for obtaining a difference output value that is a difference from the average value of
3, the differential output value of the differential amplifier 23 and the threshold setting device 2
5 and a comparator 24 for comparing the set threshold value and outputting a bead end detection signal.

First, the principle of a method for detecting a bead end will be described with reference to FIG. The welding wire 3a of the electrode nozzle 3 performs welding along the welding line 2 of the T-shaped workpiece 1 while controlling the groove following 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 FIG. 3A because the distance between the welding wire 3a and the workpiece 1 changes according to the change in the rotational position as shown in FIG. Welding direction W
Maximum at the Cf point in front of the rotation in D and the Cr point behind,
The minimum value is obtained at the point R on the upright side and the point L on the lower side.

When the electrode nozzle 3 approaches the end of the existing bead 5 in the weld joint, the arc rides on the existing bead from the front Cf side of the rotation of the arc, as shown in FIGS. 6B to 6E. Then, the arc voltage at the rotation position on the Cf side gradually decreases, but the arc voltage at the rotation position on the Cr side does not change. Therefore, the rotating electrode nozzle 3
By detecting the arc voltages on the Cf side and the Cr side, respectively, and comparing the two voltages, it is understood that the electrode nozzle 3 has reached the end of the existing bead 5. Thus, by detecting the arc voltage between the Cf side and the Cr side, comparing the detected voltages to determine the difference, and comparing the difference with a threshold value set so that the bead end can be detected, the electrode nozzle is detected. That is, it is possible to determine whether or not 3 has come to the end of the existing bead 5 and perform a predetermined joining process.

Next, the operation of the bead end detecting device configured as described above will be described. First, a specific example in the high-speed rotating arc welding method in which bead end detection is performed 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 to the T-shaped work 1 by the high-speed rotating arc welding method, the switch 12 is switched to, for example, the arc voltage detector 10, and the arc voltage detector 10 is switched. Causes the integrators 13a and 13b to output the detected arc voltage that is changed by the rotation of the electrode nozzle 3. The rotation position detector 14 detects the rotation position of the rotating electrode nozzle 3 and outputs a position detection signal. Then, among the signals output from the arc voltage detector 10, for example, 315 ° to 45 ° as shown in FIG. 4 on the front side (hereinafter referred to as Cf side) in the welding progress direction W (G is the origin, R at an angle to the direction, the same applies hereinafter to) a is 90 ° angular range S ₁ and the welding direction W rear side (hereinafter, the angle range of a, for example 135 ° to 225 ° is 90 ° as Cr side) S _The timing pulse generator 15 outputs the 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 of the angular range S ₁ of the Cf side of 90 °, the integrator 13b in the Cr-side 90 ° C.
Are integrated over the angle range of
The integrated value of the signal integrated by a and 13b is input to the first differential amplifier 16. Thus, the integrators 13a,
Integrating at 13b is because the arc voltage waveform has noise,
This is so as not to be affected.

The seeking an integration values S ₁ of the first differential amplifier 16 in the integrator 13a, a deviation signal ΔS is the difference between the integrated value S ₂ by the integrator 13b. Therefore, the deviation signal ΔS
And the threshold value S _0, and when the deviation value ΔS exceeds the threshold value S ₀ , the fact that the electrode nozzle 3 comes to the end of the existing bead 5 of the T-shaped workpiece 1 is shown in FIGS. ) Can also be detected. Note that L in FIG. 6 indicates a bead end detection signal by a laser sensor prepared for confirming such a detection method.

However, the deviation signal ΔS output from the first differential amplifier 16 depends on various factors such as disturbance of the arc and fluctuation of the wire feeding speed, as shown in FIG. 9 (i). The waveform may be distorted. For this reason,
If the deviation signal ΔS even bead end earlier welded joint from being detected bead end erroneously to exceed the threshold S ₀ is generated.

Therefore, in this embodiment, in order to eliminate such an erroneous detection, the following signal processing is performed to detect a bead end. First, the average value calculator 18 causes the average value of the deviation signal just before the bead end of the welded joint to be calculated with respect to the deviation signal ΔS output from the first differential amplifier 16. 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, of the movement distances taught in advance from the welding start end A to the bead end D of the welding torch 3 shown in FIG. The driving signal is output to the average value calculator 18 only during a fixed movement distance l _S from the position B to the position C near the bead end of the weld joint. Therefore,
The average value calculator 19 operates only during the fixed movement distance l _S as shown in FIG. 9 (i), and calculates the average value of the deviation signal ΔS output from the first differential amplifier 16 per predetermined movement 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 the average value calculator 6 and the average value of the deviation signals of the average value calculator 18 is obtained, 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, accumulates the difference output value of the second differential amplifier 19 every arc rotation from the end of the drive signal, and calculates the accumulated value. Output to the bead end determiner 21. The bead end determiner 21 obtains a change amount V of the integrated value output from the integrator 20 per a predetermined time, compares the change amount V with a predetermined threshold value, and compares the change amount V with a predetermined threshold value. When the electrode nozzle 3 exceeds T
It outputs a bead end detection signal indicating that it has come to the end of the existing bead 5 of the character-shaped work 1.

The operation of the bead end determiner 21 will be described in more detail with reference to FIG. 2. In the average value calculator 22 of the bead end determiner 21, the time T ₀ of the output か ら from the integrator 20 is obtained.
From ΔT / 2, an average value Ｔ up to T ₀ + ΔT / 2 is obtained, and the average value 出力 is output to the differential amplifier 23. The differential amplifier 23 obtains the difference between the integrated value か ら from the integrator 20 and the average value の of the average value operation value 22 and outputs the difference signal to the comparator 24. It is an example of a method of calculating the amount of change V of the integrated value per predetermined time. {Example T ₀ = 1, Δ1 = 1 second}

The comparator 24 compares a change amount V of the integrated value output from the differential amplifier 23 per predetermined time with a predetermined threshold value set by the threshold value setting device 25, and the difference is a threshold. When the value exceeds the value, a bead end detection signal indicating that the electrode nozzle 3 has come to the end of the existing bead 5 of the T-shaped work 1 is output. Therefore, the electrode nozzle 3 is moved to the existing bead 5 by the bead end detection signal output from the comparator 24.
Can be detected with high accuracy. The threshold value set by the threshold value setting unit 24 is set to a value indicating that the change amount V of the integrated value の of the integrator 20 has increased sharply and has reached the end position. At the moment when V exceeds the threshold value, it is determined to be the bead end.

As described above, 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 value to be integrated with the integrated value 20 is set to zero level so that the change in the deviation signal can be regarded as a steep change, thereby causing the arc disturbance. In addition, it is not 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 like.

Also, the integrated value of the integrator 20 is immediately compared with a threshold value to detect a bead end without detecting a bead end, but by comparing a change amount of the integrated value per predetermined time with a threshold value. The reason for this is that the integrated value suddenly increases during the integration at the end of the existing bead, so the sudden change point (inflection point) of the integrated value
This is because if the end of bead is determined by finding, the bead end position can be more reliably and accurately detected. Therefore, good welding quality between the existing bead end of the welded joint and the new bead can be stably ensured.
In this embodiment, the change amount of the integrated value is regarded as the change amount per a predetermined time. However, the bead end can be detected even if the integrated value is regarded as the change amount per a predetermined number of rotations or a predetermined number of signals. Of course.

In the embodiment shown in FIG. 5, the integrator 13
The target of the arc voltage to be integrated in a and 13b is 3 on the Cf side.
Is 15 ° to 45 ° and 90 ° angular range S _1, Cr
90 ° angle range S ₂ which is 135 ° to 225 ° on the side
However, the angle range is not limited to 90 °, and it goes without saying that the bead end can be detected if the angle is 5 ° or more and 180 ° or less.

In the above-described embodiment, the arc voltage is detected by the arc voltage detector 10 and the signal is processed to detect the bead end of the welded joint.
2 is switched to the welding current detector 11 side to switch the welding current detector 1
The bead end of the welded joint can also be detected by performing signal processing on the welding current detected in step 1 in the same manner as in the above-described embodiment. In the arc voltage, the voltage at the Cf position decreases, but in the welding current, the voltage decreases at the Cf position.
The only difference is that the current at the side R position 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 welding is performed on the workpiece by the high-speed rotating arc welding method. The arc voltage waveform or the welding current waveform is integrated over two predetermined angular ranges of the arc rotation position for each rotation of the arc, and a deviation signal, which is the difference between the integrated values, is calculated for each arc rotation. The difference between the deviation signal and the average value of the deviation signal calculated in advance within a predetermined distance before the position where the welding torch starts the bead end detection control from the point in time when the detection control start position is reached is determined by one rotation of the arc. It is determined that the welding torch has reached the end of the existing bead when the amount of change per predetermined number of revolutions, predetermined time or predetermined number of signals exceeds a predetermined threshold value. The welding arc itself serves as a sensor because it performs a predetermined connection process between the bead and the newly-formed bead, and is not affected by deformation such as thermal distortion or shrinkage due to welding, bending of the wire, etc. Even if the arc voltage waveform or welding current waveform itself is disturbed due to various factors such as turbulence or fluctuations in the wire feeding speed, signal processing is performed so as to be hardly affected by the turbulence of the waveform. Without this, there is an effect that the bead end position of the welded joint is reliably and accurately detected in the welding process, and good welding quality of the existing bead, the new bead, and the bead joint of the welded joint can be stably secured.

[Brief description of the 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 determiner of the bead end detection device.

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

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

FIG. 5 is an explanatory diagram showing a rotation locus of a wire of an electrode nozzle and an aspect of a target angle range on the Cf side and the Cr side of an arc voltage integrated by an integrator.

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

FIG. 7 is a waveform diagram of a signal indicating a difference between integral 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 with respect to a weld joint.

FIG. 9 is a waveform chart showing signal waveforms at various parts of the bead end detection device.

FIG. 10 is an explanatory view showing a groove tracing control method using a conventional arc sensor.

Claims (2)

(57) [Claims] In a high-speed rotary arc welding method in which welding is performed while giving a rotating circular motion to the tip of an electrode nozzle of a welding torch and rotating an arc generated at the tip of a wire at a high speed, the arc voltage or welding current during welding and the arc current are controlled. A rotation position is detected, an arc voltage waveform or a welding current waveform is integrated for two predetermined angular ranges of the arc rotation position for each rotation of the arc, and a deviation signal, which is a difference between the integrated values, is generated for each rotation of the arc. The deviation signal is calculated from the time the welding torch reaches the position where the bead end detection control is started, and the average of the deviation signal calculated in advance within a predetermined distance before the position where the welding torch starts the bead end detection control. The difference from the value is integrated for each rotation of the arc, and welding is performed when the amount of change of the integrated value for a predetermined number of rotations, a predetermined time, or a predetermined number of signals exceeds a predetermined threshold. 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 rotating arc welding method, and a rotation position detection for detecting a rotation angle position of an electrode nozzle. Detector, two integrators for integrating detection signals of an arc voltage detector or a welding current detector, and rotational position detection of the drive signal so that the integrator integrates only in two predetermined angular ranges of arc rotation. A timing pulse generator that outputs a signal 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. An average value calculator for calculating the average value of the output deviation signals and a drive signal for operating the average value calculator only for a desired moving distance before the existing bead end of the welding torch are output. A bead end detection control timing command generator, a second differential amplifier for obtaining a difference output value which is a 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. An integrator for calculating an integrated value by integrating the differential output value of the second differential amplifier for each rotation of the arc from the end of the drive signal of the generator; a predetermined number of rotations, a predetermined time, or a predetermined number of signals of the integrated value of the integrator A bead end determiner that compares a change amount per hit with a predetermined threshold value and outputs a bead end detection signal indicating that the welding torch has come to the existing bead end when the change amount exceeds the predetermined threshold value. And a bead end detecting device.