JPH0328978B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a welding speed control method in consumable electrode arc welding in which a groove is welded while a welding torch is oscillated in the width direction of the groove. .

[Prior Art] Conventionally, this type of welding speed control method has been described in Japanese Patent Application Laid-open No. 109576/1982 and Japanese Utility Model Publication No. 36373/1982.

In consumable electrode arc welding, the welding wire feeding speed or welding speed is controlled in order to obtain a proper weld bead. In order to make this control effective, it is necessary to accurately recognize the condition of the groove (presence or absence of variation in groove width, degree of variation, etc.).

By the way, in consumable electrode type arc welding, if the welding wire feeding speed is W, the welding current is I, and the welding wire protrusion length (the protrusion length from the current-carrying tip) is l, then W=K ₁・I+K ₂・I There is a characteristic expressed as ²・l. However, K ₁ and K ₂ are proportionality constants. Now, when welding wire feeding speed W is kept constant, welding current I increases as welding wire protrusion length l becomes shorter.
When the groove width becomes narrower, the weld bead height becomes higher, so the welding wire protrusion length l becomes shorter and the welding current I increases. Conversely, when the groove width becomes wider, the welding bead height becomes lower and the welding wire protrudes more. As the length l increases, the welding current I decreases. From this, it is possible to indirectly know the fluctuation of the groove width by monitoring the fluctuation force of the welding current I, and the welding current I increases compared to the reference current value determined for the reference groove width. Alternatively, if the welding bead height decreases, the welding speed can be increased or decreased in response to the fluctuating force to maintain the weld bead height at an appropriate level.

However, the above-mentioned fluctuations in welding current are also caused by fluctuation factors other than fluctuations in groove width. The biggest factor in this variation is the surface of the base metal as a workpiece at the welding site due to inclination or bending in the groove longitudinal direction, and the welding torch holding part (the groove width direction, the distance from the welding torch side reference position (where the distance from the base metal reference position remains constant even when oscillating in the direction of the torch axis), and if the distance changes, the groove width will change. Even if there is no welding wire, the welding current I changes because the welding wire protrusion length l changes. In order to eliminate the influence of this variation, a method of controlling the welding speed while keeping the welding torch at a constant height from the surface of the base metal is disclosed in the above-mentioned Japanese Patent Laid-Open No. 109576/1983.

This conventional method constantly compares the welding current detection signal and the reference welding current signal, converts the deviation into a level to produce a welding speed deviation signal, and calculates the sum of this welding speed deviation signal and the reference welding speed signal for welding. The welding current detection signal is used as a speed command value to control the cart drive motor, but the welding current detection signal has a minimum value when the arc is near the center between the groove walls, and a minimum value when the arc is near the groove walls. Since the signal has a waveform with a maximum value, there is a problem in that the drive motor repeats speed increase and deceleration following the oscillation position.

The above-mentioned Japanese Utility Model Publication No. 57-36373 discloses that the welding current detection point is specified at the center point of the oscillation pattern, which can solve the above problem, but this prior art has the following problems. There are problems as described. In other words, the instantaneous value of the welding current at the center point of the oscillation pattern is extracted and used here, but in difficult position welding (upright or upward position), the welding current is at a low level, and droplets from the welding wire are Since the transition is also a short-circuit transition or a globular transition, the instantaneous value of the welding current is unstable.

Furthermore, in this prior art, a standard welding speed, a high welding speed, and a low welding speed are specified in advance, and when a deviation occurs between the detected welding current and the standard welding current, the high welding speed or the low welding speed is changed to the above-mentioned high welding speed or low welding speed. If the speed command is changed and the above deviation is eliminated as a result, the speed command is returned to the standard welding speed in the next oscillation half cycle, as shown in Figure 6e.
If the above deviation is not eliminated, the same speed (the above-mentioned high welding speed or low welding speed) is maintained. That is, even if a welding speed suitable for the groove width of the groove being welded is obtained, in the next oscillation half cycle, this appropriate welding speed is abandoned and welding is performed at the standard welding speed. However, the actual groove is as shown in Figure 6a.
As shown in Figure 2, the groove width changes continuously in a tapered manner to become wider or narrower. As the welding progresses, the welding speed increases as the welding progresses, and there is a risk of a hunting condition in which the welding speed repeatedly increases or decreases rapidly every half period of the oscillation, and it is difficult to obtain a uniform bead height over the entire length of the groove. be.

This invention was made to solve the above-mentioned conventional problems, and it allows the welding speed to quickly and faithfully follow changes in the groove width, stabilizes the welding speed control operation, and performs welding. The object of the present invention is to obtain a welding speed control method for consumable electrode type arc welding that can always maintain an appropriate bead height.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a welding current reference value that is initially set to a welding current measurement value that is measured as an average value of welding current for a predetermined period every oscillation half cycle. The deviation is extracted as the first welding current deviation, and the first welding speed correction command value is determined based on this first welding current deviation. The first welding method calculates a second welding speed correction command value based on the second welding current deviation obtained by adding it to the deviation measured in a half cycle, and then outputs it for a predetermined period within each oscillation half cycle. A third welding speed correction command value is obtained by adding the speed correction command value and the second welding speed correction command value output during each oscillation half cycle, and the third welding speed correction command value and the initial welding The welding speed command value obtained by adding the welding speed command value to the speed command value is used as the welding speed command value for the next oscillation half cycle.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing an example of a consumable electrode type gas-shielded arc welding apparatus (in an upward welding position) to which the present invention is applied. In the figure, 1 is a base material to be welded which has a V-shaped groove with a groove width, 2 is a ceramic backing material used in the first layer of Uranami welding, 3 is a restraining plate of base material 1, and 4 is a welding torch, 5 is a welding wire, 6 is a rail, 7 is a trolley that runs on the rail 6, 8 is a trolley drive motor,
9 is a vertical axis slider, 10 is a vertical axis slider drive motor, 11 is a left and right axis slider, 12 is a left and right axis slider drive motor, 13 is a welding torch 4 connected to base material 1
14 is a drive motor for the oscillating device; 15 is a contact type detector for detecting the surface position of the base material 1; The displacement of the surface position (height) of the material 1 is detected. This detector 15 is connected to the oscillator 13
It is also attached to the left and right axis slider 11. 16 is an arc welding power source, 17 is a current detector for detecting a welding current, and 18 is a control device, each of which has a block configuration shown in FIG.

In FIG. 2, reference numeral 19 denotes a vertical positional deviation determination circuit, which takes in the displacement (signal) detected by the detector 15 and determines whether the displacement increases or decreases. 20 is a servo amplifier that drives the vertical axis slider drive motor 10 (M4) in the direction in which the slide base moves upward or downward in accordance with the increase or decrease command output by the vertical position deviation determination circuit 19, and The distance between the surface position of the base material 1 and the slide base position of the shaft slider 9 is adjusted to a set distance H ₀ set by the vertical position setting device 21.
Thereby, the reference position of the holding part of the welding torch 4 follows the vertical displacement of the surface of the base material 1. 22 is a servo amplifier for the left and right axis slider drive motor 12 (M3), 23 is a left and right position setting device,
This is manually operated to cause the left and right axis slider 11 to perform an inching operation. Reference numeral 24 is a servo amplifier for the drive motor 14 (M2) of the oscillating device 13, and has a function of controlling the oscillating pattern. 25 is a manually operated oscillation width setting device, 26
is a manually operated oscillation period setting device. 27
is a timing signal generation circuit which generates a timing signal for control, which will be described later, based on an oscillation left end stop signal _PL of the welding torch 4, an oscillation right end stop signal _PR and an operation sequence signal from the oscillation pattern control signal of the servo amplifier 24. _P1
~Create _P7 .

The welding current (signal) output by the current detector 17 is passed through a low-pass filter 28 and then sent to an amplifier circuit 29.
is amplified. This low-pass filter 28 is provided to remove high frequency components caused by the commercial frequency of the arc welding power source 16 and noise components accompanying the transfer of arc droplets. 30 is an average value circuit which takes in the welding current I amplified by the amplifier circuit 29 and measures the welding current average value I _A in synchronization with the timing signal from the timing signal generation circuit 27. 31 and 32 are sample hold circuits, and the sample hold circuit 31 is connected to the welding torch 4.
The sample hold circuit 32 samples and holds the welding current average value I _ALR measured by the average value circuit 30 when the welding torch 4 is oscillated from the right end to the right end. The welding current average value I _ALR measured by the value circuit 30 is sampled and held. Sample hold circuit 31, 3
Average value of welding current held in 2
Both I _ALR and I _ARL are led to an adder circuit 33.
The adder circuit 33 adds the value I _AS = every half cycle of the oscillation rate.
(I _ALR + I _ARL )/2 (hereinafter, this value will be referred to as the welding current measurement value) is calculated and updated. The welding current measurement value I _AS is read into the A/D converter 34 and then guided to the D/A converter 35 and also to the differential amplifier circuit 36 . The A/D converter 34 receives a reading command created by an operator operation after welding starts. Further, the D/A converter 35 holds the welding current measurement value I _AS inputted by the read command as the welding current reference value I _AC . Then, the differential amplifier circuit 36 amplifies the welding current deviation ΔI between the welding current reference value I _AC and the welding current measured value I _AS and sends it to the dead zone circuit 37 . Dead band circuit 37 performs dead band processing on welding current deviation ΔI and outputs a processed signal ΔI _DN (hereinafter referred to as first welding current deviation) to first level conversion circuit 38 and deviation update processing circuit 39.

The first level conversion circuit 38 converts the level of the first welding current deviation I _DN into a first welding speed correction command value ΔS _{DN, and converts this first welding speed correction command value ΔS DN into} an oscillation half cycle. A switch circuit 40 that is conductive only for a predetermined period within the oscillation half cycle each time.
The signal is output to the adder circuit 41 via the adder circuit 41. On the other hand, the deviation update processing circuit 39 adds and updates the first welding current deviation ΔI _DN every oscillation half cycle, and converts the processed signal ΔI _DNSUM (hereinafter referred to as the second welding current deviation) into the second welding current deviation. It is output to the level conversion circuit 42. This level conversion circuit 42 converts the second welding current deviation
The level of I _DNSUM is converted into a second welding speed correction command value ΔS _DNSUM , and this second welding speed correction command value ΔS _DNSUM is output to the addition circuit 41 over the oscillation half period. The addition circuit 41 receives the first welding speed correction command value ΔS _DN from the switch circuit 40 and the second welding speed correction command value ΔS DN from the second level conversion circuit 42.
and the welding speed correction command value ΔS _DNSUM are added and output as the third welding speed correction command value ΔS _N.

Further, 43 is an adder circuit, and this adder circuit 43 receives the initial welding speed command value S _KO created by the initial welding speed command device 44 and the third
is added to the welding speed correction command value ΔS _N and is supplied to the servo amplifier 40 for driving the trolley drive motor 8 (M1). Reference numeral 46 denotes an inching speed setting device for manually inching the trolley 7.

Note that, as shown in FIG. 3, the adder circuit 33 includes an operational amplifier A1, and the differential amplifier circuit 3
6 is configured with an operational amplifier A2. The differential amplifier circuit 36 also includes an abnormal deviation detection circuit 36.
A is attached, and this abnormal deviation detection circuit 36
A is operational amplifier A3, A4, voltage comparator C1~
It is composed of C3 and NOT gate G1, and drives analog switch AS1 in order to cope with short-term arc breakage and arc instability that occur during welding. Furthermore, as shown in FIG. 4, the dead band circuit 37 includes operational amplifiers A5 to A7, and outputs a zero value when the welding current deviation ΔI is within the dead band (E ₂ to −E ₂ ). The first level conversion circuit 38 includes operational amplifiers A8 and A9, and the deviation update processing circuit 39 includes a sample hold circuit SH1, a sample hold circuit SH2 that holds the output of the sample hold circuit SH1, and an operational amplifier. The switch circuit 40 includes analog switches AS2 and AS3, and the adder circuit 41 includes an operational amplifier A10.
It consists of 11 parts. Further, the second level conversion circuit 42 includes operational amplifiers A12 and A13, and the addition circuit 43 includes an operational amplifier A14.

Hereinafter, the operation of the above device will be explained based on the timing signals _P1 to _P7 shown in FIG.

In FIG. 5, I indicates the welding current signal input to the average value circuit 30 (actually, it is a sinusoidal waveform with distortion in synchronization with the oscillation period of the welding torch 4, but for convenience, (shown as a triangular wave). The oscillation left end position signal P _L and the oscillation right end position signal P _R are each oscillated by the oscillator 1.
3 is a pulse that rises when it reaches the left end L and right end R and stops, and then falls when it starts moving in the opposite direction. The period t ₀ is the operating period of the welding torch 4 within the oscillation half cycle (the stopping period is period). The timing signal P ₁ is the signal P _L ,
The _timing signal P ₂ is an extremely narrow pulse that rises in synchronization with the rise of _P It becomes a command. The timing signal P ₃ is a pulse with an extremely narrow width that is generated in synchronization with the even numbered sequence of the timing signal P ₁ and serves as a sample/hold command for the sample and hold circuit 31 . When the timing signals P ₂ and P ₃ are both at H level, they serve as a sampling command, and when they are at L level, they serve as a hold command.

Further, the timing signal _P4 is a pulse with a predetermined width _tDS that rises periodically at the falling edge of the position signals P _L and _PR , and the average value circuit 30 is reset during the H level period of the timing signal _P4 . , welding current average values I ALR and _{I ARL} for periods t _ALR and t _ARL from the fall of the signal to the fall of the timing signals P ₃ and P ₂ , respectively, are calculated. In addition,
Normally, the pulse widths of the position signals _PL and _PR are set to be equal, so the periods t _ALR and t _ARL are equal. Further, the period t _DS of the timing signal P ₄ is provided to eliminate the influence of variations in the oscillation rate width on the groove width. For example, if the oscillation half cycle is about 1 second, the period t _DS is about 300 msec.

Furthermore, the timing signal _P5 is the timing signal
This pulse has an extremely narrow width and rises in synchronization with the falling edge of _P1 , and serves as a sample/hold command to the sample/hold circuit SH1 of the deviation update processing circuit 39 shown in FIG. Timing signal _P6
is an extremely narrow pulse that rises in synchronization with the falling edge of the timing signal _P5 , and is a sample hold circuit of the deviation update processing circuit 39 shown in FIG.
This is a sample/hold command for SH2.
Both of these timing signals P ₅ and P ₆ serve as a sampling command when at an H level, and serve as a hold command when at an L level. The timing signal _P7 is a pulse with a predetermined width _tS that rises in synchronization with the falling edge of the timing signal _P1 , and is
0 switch ON/OFF command.

Now, prior to starting welding, welding condition parameters are set by the operator. When oscillation welding is started, an operation is started to maintain a constant distance between the reference position of the holding part of the welding torch 4 and the surface of the base metal 1, and the welding current is detected through the current detector 17. The welding current is passed through a low-pass filter 28 and an amplifier 29 to an average value circuit 3.
It is input to 0. Among the welding current average values I _A calculated by the average value circuit 30, the average value I _ALR of the above period t _ALR
is held in the sample hold circuit 31 by the timing signal _P3 , and the average value of the above period t _ARL
I _ARL is held in the sample hold circuit 32 by the timing signal _P2 . Then, the held average values I _ALR and I _ARL are input to an adder circuit 33 with a gain of 1/2, and the welding current measurement value is output as the output.
We get I _AS = (I _ALR + I _ARL )/2. This welding current measurement value I _AS is updated every oscillation half cycle by timing signals P ₃ and P ₂ (including cases where the value does not change) in accordance with the oscillation welding signal. Here, the meaning of using the value I _AS as the welding current measurement value is to eliminate the variation in the average value of the welding current measured every half cycle of the oscillation, which occurs even when there is no increase or decrease in the groove width. This is to measure changes in welding current due to fluctuations in width at every oscillation half cycle.

After welding starts, the oscillator checks the welding condition parameters and readjusts each parameter if necessary. The welding current set value _SKO is adjusted using the initial welding speed command device 44. After completing the adjustment, the operator issues a read command to the A/D conversion circuit 34 by operating, for example, a read push button on an operation panel (not shown). This reading command is for initializing the welding current reference value, and the A/D conversion circuit 34 that receives this command takes in the above-mentioned welding current measurement value I _AS from the addition circuit 33 and converts it into a digital signal value. It is converted and sent to the D/A conversion circuit 35. The D/A conversion circuit 35 converts the digital measured value I _AS into an analog signal value and holds it as a welding current reference value I _AC until the end of welding.
After setting the welding current reference value I _AC , switch SW1 in Fig. 4, which had been in the ON state, is turned OFF, and switch SW2 in Fig. 4, which had been in the OFF state, is turned ON to control the welding speed. is started. Thereafter, the welding current measurement value I _AS measured every half cycle of the oscillation is compared with the welding current reference value I _AC , and the welding current deviation ΔI=G・(I _AS −I _AC ) is calculated by the differential amplifier circuit 36. (where G is the gain).

Here, the abnormal deviation detection circuit 36A shown in FIG.
I will explain about it. Note that this abnormal deviation detection circuit 36A is omitted from illustration in FIG. The abnormal deviation detection circuit 36A is provided with a set value _E1 , and when the absolute value of the output ΔI of the differential amplifier circuit 36 becomes larger than the set value _E1 , the analog switch AS1 is turned on and the differential amplifier circuit 3 is turned on.
The output ΔI of 6 is connected to ground via a resistor. As a result, the dead band circuit 37 in FIG.
Since =0 is input, the welding speed (traveling speed of the trolley 7) is maintained at the speed before ΔI=0 was input. In addition, the differential amplifier circuit 3
When the absolute value of the output ΔI of 6 is within the set value E ₁ ,
The analog switch AS1 is in the OFF state and is in a normal state, that is, the output ΔI of the differential amplifier circuit 36 is input to the dead band circuit 37 as is. In this way, the abnormal deviation detection circuit 36A can deal with short-term arc breakage and arc instability that occur during welding. Note that the set value _E1 is set to, for example, a value of about 10 amperes.

Now, the welding current deviation ΔI from the differential amplifier circuit 36 is input to the dead zone circuit 37 shown in FIG. The dead band circuit 37 is provided with a dead band setting value ±E ₂ , and when the deviation ΔI is −E ₂ ≦ΔI ≦E ₂ , ΔI _DN =
0, when ΔI>E ₂ , ΔI _DN = ΔI−E ₂ , ΔE ₂ <−E ₂
In this case, the dead band circuit 37 outputs a signal ΔI _DN that has been subjected to dead band processing such that ΔI _DN =ΔI+E ₂ .
Here, the set value _E2 is set to, for example, a value of about 1 ampere. The current deviation ΔI _DN obtained by the dead zone circuit 37 is defined as a first welding current deviation, and this first welding current deviation ΔI _DN is sent to the first level conversion circuit 38 and the deviation update processing circuit 39 . The first level conversion circuit 38 converts the signal value level of the first welding current deviation ΔI _DN into a first welding speed correction command value ΔS _DN , and the speed-converted first welding speed correction command value ΔS _DN . is sent to the adder circuit 41 via the analog switch AS2 of the switch circuit 40. Note that the analog switch AS2 is turned on when the timing signal _P7 is at the H level (predetermined width _ts ), and turned off when the timing signal P7 is at the low level. Conversely, the analog switch AS3 is turned OFF when the timing signal P7 is at the H level, and turned ON when the timing signal _P7 is at the L level. As a result, the first welding speed correction command value ΔS _DN is input to the addition circuit 41 over a predetermined period t _S within each oscillation half cycle. Here, the period t _S
For example, in the upward first layer welding of this example, 300
It is about msec. The relationship between this period t _S and the left and right end stop periods P _L and P _R of the oscillation is preferably such that t _S ≦P _L , P _R .

On the other hand, the sample hold circuit SH1 of the deviation update processing circuit 39 uses the first welding current deviation ΔI _DN measured in the current oscillation half cycle using the timing signal _P5 , and the sample hold circuit SH2 according to the timing signal _P6 . Sample and hold the added value ΔI _DNSUM with the output ΔI _DN-1SUM . Here, ΔI _DN-1SUM = _N-1 〓 ^N=0 ΔI _DN (However, ΔI _D0 = 0), and this value is the current from the completion of setting the welding current reference value I _AC to the previous half cycle of oscillation. This is the accumulated value (total value) of the deviation ΔI _DN , and the obtained additional value ΔI _DNSUM is the accumulated value (total value) of the welding current deviation ΔI _DN from the completion of setting the welding current reference value I _AC to the current oscillation half cycle. ). In other words, the deviation update processing circuit 39 updates the welding current deviation ΔI _DN measured every oscillation half cycle from the time when the setting of the welding current reference value I _AC was completed and the speed control operation started until now.
Functions as a register to accumulate. Note that, as a matter of course, the welding current deviation ΔI _DN takes values of 0, positive, and negative.

The welding current deviation ΔI _DNSUM thus obtained by the sample and hold circuit SH1 is set as a second welding current deviation, and this second welding current deviation ΔI _DNSUM is sent to the second level conversion circuit 42. The level conversion circuit 42 converts the second welding current deviation ΔI _DNSUM into a second welding current deviation ΔI DNSUM.
The signal value level is converted into a welding speed correction command value ΔS _DNSUM and sent to the addition circuit 41. The addition circuit 41 receives the first welding speed correction command value _ΔSDN from the switch circuit 40 and the second level conversion circuit 42.
The third welding speed correction command value ΔS _N (= _{ΔS DN}
+ΔS _DNSUM ) and sends it to the adder circuit 43 at the next stage.

Then, the addition circuit 43 outputs the initial welding speed command value S _KO set by the variable resistor VR1 in the initial welding speed command device 44 and the third
and the welding speed correction command value ΔS _N and send the obtained added value S _N+1SUM (=S _KO +ΔS _N ) to the servo amplifier 45 as the welding speed command value in the next oscillation half cycle. Depending on the welding current reference value
Welding speed [speed of trolley drive motor 8 (M1 ₎ ] so as to cancel the deviation ΔI between I AC and welding current measurement value I _AS
By controlling the increase/decrease in the groove width, it is possible to obtain a weld bead that adapts to the desired increase/decrease variation in groove width [see FIG. 6a].

As described above, in this embodiment, welding is performed while correcting the initially set welding speed command value S _KO by the third welding speed correction command value ΔS _N every oscillation half cycle, and The welding speed command value S _N+1SUM in the oscillation half cycle is the initial welding speed command value
S _KO and the first welding current deviation ΔI _DN and the second welding current deviation ΔI _DNSUM measured in the Nth oscillation half cycle, respectively.
Addition value to the third welding speed correction command value ΔS _N, which is the sum of the welding speed correction command value ΔS _DN and the second welding speed correction command value ΔS _DNSUM [see Fig. 6 c, d]
becomes. In other words, welding speed command value S _N+1SUM
is the addition value of the welding speed command value S _NSUM in the Nth oscillation half cycle and (ΔS _N −ΔS _N-1 ),
The speed command value ΔS _{N obtained by measuring the current deviation in this time (Nth oscillation half cycle) is the welding speed correction command value ΔS N obtained} in the previous time (N-1st oscillation half cycle). Only when there is an increase or decrease with respect to _-1 , the welding speed command value S _NSUM is corrected by the amount of the increase or decrease and is set as the welding speed command value for the next N+1st oscillation half cycle.

By the way, the first welding speed correction command value ΔS _DN and the second welding speed correction command value ΔS _DNSUM created from the welding current deviation ΔI _DN and ΔI _DNSUM are explained below.
Explain the meaning of. Conversion ratio of second welding speed correction command value ΔS _DNSUM to second welding current deviation ΔI _DNSUM (second level conversion circuit 42
gain) is fixed, so only the second welding speed correction command value ΔS _DNSUM is used as the initial welding speed command value.
When calculating the welding speed command value by adding it to S _KO , the groove width fluctuation, which is indirectly detected as the welding current fluctuation, and the second welding speed correction command value ΔS _DNSUM
A deviation inevitably occurs between the welding speed and the welding speed, resulting in poor responsiveness. Therefore, a new first welding speed correction command value ΔS _DN is introduced, and the superposition of the first welding speed correction command value ΔS _DN and the second welding speed correction command value ΔS _DNSUM is used as the welding speed correction command value. By doing so, sufficient followability can be obtained. This is because the first welding speed correction command value ΔS _DN complements the excess or deficiency of the welding speed caused by the second welding speed correction command value ΔS _DNSUM , and also has a differential element with respect to increases and decreases in the groove width. This is because a rapid response effect can be obtained by using the same method.

In addition, in the case where the groove width fluctuates as shown in FIG. 6a, the output pattern of the welding speed command value according to the embodiment of the present invention is shown in FIGS. 6c and d, and the welding speed command according to the conventional technology The value output pattern is shown in FIG. 6e. However, Fig. 6c shows the output pattern of the ideal welding speed command value, and Fig. 6d shows the ideal welding speed command value output pattern.
shows the output pattern of the actually obtained welding speed command value.

Further, in the above embodiment, the speed control method in oscillated welding was explained, but even in straight welding in which the welding torch 4 is not oscillated, signals corresponding to the position signals P _L and P _R in FIG. 5 or 6 b can be used. By creating , the method of the present invention can be applied.

[Effects of the Invention] As described above, in the present invention, the welding speed command value created for each oscillation half cycle is a third welding speed command value created by superimposing the first welding speed correction command value and the second welding speed correction command value. The first welding speed correction command value is obtained as the addition value of the welding speed correction command value of It has a differential element for the increase/decrease fluctuation in the groove width, and the welding speed command value is created by correcting the groove fluctuation in the welding speed that reached the previous oscillation half cycle. It is possible to adapt to fluctuations substantially faithfully and quickly, the welding speed control operation is smooth and stable, and the uniformity of the weld bead height can be improved compared to the conventional method.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram showing an example of a welding device embodying the present invention, Fig. 2 is a block diagram of a control device in the above embodiment, and Figs. 3 and 4 both show a part of the above control device in detail. 5 is a waveform time chart of the timing signal in the above embodiment, FIG. 6a is a diagram showing an example of variation in groove width, and FIG. 6b is an output of the oscillation left and right end stop signals. Figures 6c and 6d are diagrams showing the pattern of the welding speed command value in the above embodiment, and Figure 6e is a diagram showing the pattern of the welding speed command value in the conventional welding speed control method. be. In the figure, 1...Base material as the object to be welded, 4
... Welding torch, 13 ... Oscillating device, 19
... Vertical positional deviation determination circuit, 30 ... Average value circuit, 31, 32 ... Sample hold circuit, 33
... Addition circuit, 34 ... A/D conversion circuit, 35 ...
...D/A conversion circuit, 36...Differential amplifier circuit, 37
... Dead band circuit, 38 ... First level conversion circuit, 39 ... Deviation update processing circuit, 40 ... Switch circuit, 41 ... Addition circuit, 42 ... Second level conversion circuit, 43 ... Addition circuit .

Claims (1)

[Scope of Claims] 1. In consumable electrode arc welding in which arc welding is performed while the welding torch is oscillated in the width direction of the groove while maintaining a constant distance between the welding torch holder and the surface of the workpiece, Measure the average value of the welding current for a predetermined period within each oscillation half cycle of the welding torch, and initialize this welding current measurement value as the welding current reference value. After initializing the welding speed, every oscillation half cycle. Compare the welding current measurement value measured in the current welding current reference value with the welding current reference value, and measure the deviation between the welding current measurement value and the welding current reference value in the current oscillation half cycle as a first welding current deviation. , a first welding speed correction command value is determined based on this first welding current deviation, and the first welding current deviation is added to the deviation measured in the previous oscillation half cycle to perform the second welding. After determining the current deviation and determining the second welding speed correction command value based on this second welding current deviation, the first welding speed correction command value and each oscillation rate are output for a predetermined period within each oscillation half cycle. A third welding speed correction command value is obtained by adding the above-mentioned second welding speed correction command value output during a half cycle, and this third welding speed correction command value and the initial welding speed command value are added. A welding speed control method for consumable electrode type arc welding, characterized in that the welding speed of the next oscillation half cycle is controlled based on the welding speed command value obtained. 2. The consumable electrode type arc according to claim 1, wherein the welding current measurement value is an arithmetic average value of welding current average values for a predetermined period within two consecutive oscillation half cycles. Welding speed control method for welding.