JPS6320163A - Groove adaptive control method for consumable electrode type arc welding - Google Patents

Abstract

PURPOSE:To faithfully follow up to the variation in the groove width a welding speed and to realize the weld line the right and left profiling control having a high accuracy by finding the deviation by comparing the welding current measurement value to be measured on each oscillation half period with the initially set welding current reference value and performing the correction based on this deviation. CONSTITUTION:The deviation is taken off by comparing the welding current measurement value measured on each oscillation half period with the initially set welding current reference value, in case of performing an arc welding with oscillating 13 a welding torch 4 in the groove width direction. the deviation measured at the oscillation half period of this time is then added to the deviation measured at the oscillation half period of up to the previous time and in case of the deviation after the addition being increased or decreased for the deviation measured at the oscillation period of up to the previous time the welding speed command value made at the oscillation half period of this time is corrected by the speed portion corresponding to the above increase or decrease portion, the welding speed command value of the oscillation half period of the next time is outputted and the welding speed is controlled.

Description

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

[Conventional technology]

Conventionally, this type of groove adaptive control method was
There is one described in Publication No.-36373.

In consumable electrode arc welding, in order to obtain a proper weld bead, the oscillation width of the welding torch is adjusted according to the groove width, and the welding wire feeding speed or welding speed is controlled to adjust the weld bead height. At the same time, the welding line is controlled to follow left and right to prevent the weld bead from being biased or meandering toward one end or the other of the left and right ends of the groove. To enable this control:
It is necessary to accurately check the condition of the groove (presence of variation in groove width, degree of variation, position of weld line, etc.).

By the way, for welding using one set of consumable electrodes, welding wire feeding speed W, welding current I, welding wire protrusion length (protrusion length from the current-carrying tip) l, then yw- + -1 + 2
・I2 ・There is a characteristic □ that is −d by l. However, KI,
Kg is a proportionality constant. Now, when welding wire feeding speed W is kept constant, when welding wire protrusion length l becomes shorter, welding current {circle around (2)} increases.

When the groove width becomes narrower, the weld bead height increases, so the welding wire protrusion length l becomes shorter, and the welding current I' becomes lower, so the welding wire protrusion length l becomes longer and the welding current ■ decreases! From this, by monitoring the variation in welding current 1, it is possible to indirectly know the variation in groove width.
If the welding current □ increases or decreases compared to the reference current value determined for the base groove width, the welding speed is increased or decreased in accordance with the variation to increase or decrease the weld bead height. can be maintained at an appropriate height.

However, the above-mentioned fluctuations in the welding current are also caused by fluctuations in the groove width. The biggest factor in this variation is the inclination or bending of the base metal toward the back of the groove at the welding site. This is a change in the distance □ between the reference position on the welding torch side, where the distance from the base metal reference position remains constant even when oscillating, and when this distance changes, even if the groove width does not change, Since the protrusion length l changes, the welding current I changes. In order to eliminate the influence of this variation, Japanese Patent Application Laid-Open No. 55-109576 discloses a method of controlling the welding speed while keeping the welding torch at a constant height from the surface of the base material.

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 when the arc is near the center between the groove walls, the welding current detection signal becomes the minimum value.
Since the signal has a waveform that reaches its maximum value when the arc is near the groove wall, there is a problem in that the drive motor repeatedly speeds up and decelerates 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, here we extract and use the instantaneous value of the welding current at the center point of the oscillation pattern, but in difficult position welding (upright or upward position), the welding current is at a low level, and droplets from the welding wire 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. Change the speed command, resulting in
If the above deviation is eliminated, as shown in Figure 7,
In the next oscillation half cycle, the speed command is returned to the reference welding speed, and if the deviation is not eliminated, the same speed (the high welding speed or the 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, in the actual groove, the width of the groove changes continuously in a tapered shape, from wide to narrow, so in the above prior art, the standard welding speed set at the start of welding and the appropriate welding speed for the groove width cannot be determined. The difference in welding speed increases as welding progresses, and there is a risk of a hunting situation in which the welding speed repeatedly increases or decreases rapidly every half cycle of the oscillation, making it difficult to obtain a uniform bead height over the entire groove length. There's a problem.

Conventional welding line left/right tracing control is, for example,
As shown in Publication No. 7-36373, the instantaneous value of welding current is picked up at the left end point or the right end point of the oscillation pattern of the welding torch, and this is stored in a memory device, and the instantaneous welding current value is then detected. is compared with the above-mentioned stored current value by a comparator, and based on the comparison result, the motor that performs left and right tracing of the welding line is controlled. However, since this method uses the instantaneous value of the welding current, which is unstable as described above, it may lead to malfunction, especially under welding conditions where the arc is unstable, and it is difficult to obtain good tracing accuracy. , this instantaneous welding current value is taken into the comparator and memory unit after passing through a low-pass filter that causes a time delay, so there is a discrepancy between the timing at which this welding current is taken in and the actual position of the welding torch. This also causes a reduction in tracing accuracy.

Conventionally, the oscillation width of the welding torch has been controlled by increasing or decreasing the oscillation width based on the welding speed, as shown in the above two publications, but the welding speed and groove width are always 1:1. Therefore, when performing multi-layer welding, the relationship between the reference welding speed and oscillation width for each layer should be determined in advance through experiments, etc., corresponding to the voltage and current conditions that differ for each layer. There is a hassle of having to set and adjust it.

This invention was made in order to solve the above-mentioned conventional problems, and it is possible to make the welding speed faithfully follow changes in the groove width, and also realize accurate and highly accurate left and right tracing control of the weld line. It is an object of the present invention to provide a groove adaptive control method for consumable electrode arc welding, which is capable of controlling the oscillation width without the need for changing setting conditions even in multilayer build-up welding.

[Means to solve the problem]

In order to achieve the above object, in the first invention, fa) a welding current measurement value measured every oscillation half cycle is compared with an initially set welding current reference value, and the deviation is extracted. The deviation measured in the oscillation half cycle is added to the deviation measured in the previous oscillation half cycle, and if the deviation after addition increases or decreases from the deviation measured in the previous oscillation cycle, then The welding speed command value created for the next oscillation half cycle is corrected by the speed corresponding to the above increase/decrease, and the welding speed command value for the next oscillation half cycle is calculated. In the second invention, the welding current average value in a predetermined section at the end side position is taken out, and the oscillation center position of the welding torch is corrected every predetermined oscillation cycle based on the deviation between the two welding current average values. In addition, after initially setting the sum of tc + the average value of both welding currents as the oscillation width current reference value, the sum of the average values of both welding currents measured every oscillation cycle is compared with the oscillation width current reference value. According to the deviation, the oscillation width is increased or decreased in accordance with the magnitude of the deviation.

[Embodiments 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 (upward welding position) to which the present invention is applied. In the figure, 1 is a V with groove width.
A base material having a mold opening, 2 a ceramic backing material used in the first-layer Uranami welding, 3 a restraining plate for the base material, 4 a welding torch,
5 is a welding wire. 6 is a rail, 7 is a cart that runs on the rail 6, 8 is a cart 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 an oscillating device that oscillates the torch in the thickness direction and left-right direction of the 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, and detects the displacement of the surface position (height) of the base material 1 with respect to the slide base position of the vertical axis slider 9. This detector 15 is attached to the left-right axis slider 11 together with the oscillating device 13. 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 J detector 15 and determines whether the displacement is increased or decreased. 20 is a servo amplifier which 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 drives the vertical axis slider The distance between the surface positions of the base material 1 with respect to the slide base position 9 is adjusted to the set distance Ho 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-right axis slider drive motor 12 (M3), and 23 is a left-right position setting device, which is manually operated to cause the left-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, and □26 is a manually operated oscillation period setting device.

Reference numeral 27 is a timing signal generation circuit, and the welding torch 4 receives the oscillation pattern control signal from the servo amplifier 240.
Based on the oscillation left end stop signal PL, the oscillation right end stop signal PII, and the operation sequence signal, control timing signals P, -P, which will be described later, are created.

The welding current (signal) output by the current detector 17 is passed through a low-pass filter 28 and then amplified by an amplifier circuit 29.

This low-pass filter 28 is provided to remove commercial frequency components and noise components associated with transfer of arc droplets. 30 is an average value circuit which takes in the welding current amplified by the amplifier circuit 29 and generates the welding current average value (
(hereinafter referred to as gate current measurement value) 'IAs, oscillation left end side welding current average value IAL, oscillation right end side welding current average value! , is calculated. A sample hold circuit 31 samples and holds the welding current measurement value IAl. The welding current measurement value rAs held in the sample hold circuit 31 is read into the A/D conversion circuit 32 and then guided to the D/A conversion circuit 33.
The signal is guided to a differential amplifier circuit 34. The A/D conversion circuit 32 receives a reading command created by an operator operation after welding starts. Further, the D/Δ conversion circuit 33 holds the manually input welding current measurement value IAS as the welding current reference value IAC. The differential amplifier 34 amplifies the welding current deviation Δ■ between the welding current reference value IAC and the welding current measurement value IAs (detected every half cycle of the oscillation rate) and sends it to the dead band circuit 35. Reference numeral 36 denotes a deviation update processing circuit, which has a circuit configuration as shown in FIG. 3, and updates the welding current deviation Δ■ by adding it every half cycle of the oscillation rate. 37 is an amplifier circuit, 3
Reference numeral 8 denotes an adder circuit which calculates the welding speed setting value S created by the initial welding speed setting device 39. and the welding speed deviation ΔS whose level has been converted by the amplifier circuit 37, and the sum is supplied to the servo amplifier 40 for driving the truck drive motor 8 (Ml). Reference numeral 41 denotes an inching speed setting device for manually inching the trolley 7.

As shown in FIG. 3, the dead band circuit 35 has operational amplifiers OP+, OPz, and OF2, and has a welding current deviation Δ.
When ■ becomes less than the dead band setting value -E1, the current deviation ΔI
is amplified by a gain G1=R3/(Rz + VR) and output, and when the welding current deviation ΔI exceeds the dead band lower limit value E2, the gain G,=R.

/ Amplify and output by (R2+VRI). In addition, G2
<Gl is desirable. G1 is a gain during deceleration, and G2 is a gain during speed increase. When the welding current deviation Δ■ is within the dead band (E2 to -E+), a zero value is output. Letting the output of this dead zone circuit 35 be ΔID, the output is supplied to the deviation update processing circuit 36. The deviation update processing circuit 36 includes a sample and hold circuit SHE, a sample and hold circuit SH2 that holds the output of the sample and hold circuit SH, and an operational amplifier op. Δl1lIN and sample hold circuit SH2 output Δ
Sends the added value of IDN-1sLI9 (deviation of previous oscillation half cycle). Here, ΔIDN-l5U)
1-ΣΔIo++ (ΔIoo=0), and this value is the total value of the current deviation ΔIn from the setting of the welding current reference value IAC to the previous oscillation half cycle. In addition, Δ
I takes on 0, positive and negative values. This additional value ΔT, □
UM is converted to the welding speed command signal level by the operational amplifier OP5 and becomes the welding speed deviation (signal) ΔSN, which is added to the initially set welding continuous setting value SKO, and this added value SH
++suM is supplied to the servo amplifier 4° as a welding speed command (signal). Note that the switches sw, , and SW2 are turned on until the setting of the welding current reference value ■Ac and the setting of the welding speed set value SXO are completed, respectively, and are turned off in synchronization with the setting operation.

Next, a circuit section for controlling left and right welding line tracing will be explained. Reference numeral 42 denotes a sample hold circuit, which outputs the average value IA of the oscillating left end side welding current sent out by the average value circuit 30.
Sample L and make it bold. Reference numeral 43 denotes a sample and hold circuit which samples and holds the oscillation right-end side warm contact method average value TAR sent out by the average value circuit 30. Reference numeral 44 denotes a differential amplifier circuit, which derives the oscillating left end side welding current average value ■1 and the oscillating right end side welding current average value lAl1, and detects the deviation between the two.

This deviation ΔIAL-11-IAL-I□ is input to the left-right positional deviation determination circuit 46 through the dead zone circuit 45. The left-right positional deviation determination circuit 46 determines how far the oscillation center (center position in the groove width direction) of the oscillation pattern is shifted from the left and right, that is, the left and right ends of the groove width,
A slider shift command corresponding to the amount of deviation is supplied to the servo amplifier 22.

Hereinafter, the operation of the above device will be explained using a timing signal P shown in FIG.
, ~P8 will be explained.

In FIG. 4, ■ indicates a welding current signal input to the average value circuit 3o (actually, it has a sine wave shape synchronized with the oscillation period, but for convenience of explanation, it is shown as a triangular wave). The oscillation left end stop signal PL and the oscillation right end stop signals P and l are pulses that rise in synchronization with the timing when the oscillation device I3 reaches the left end and right end and stop, respectively, and fall in synchronization with the timing when the oscillation device I3 starts moving next (i.e., welding). The pulse generated during the oscillation stop period of the torch 4) and the period t. indicates the operating period of the welding torch 4 within the oscillation half cycle. The timing signal P1 is a narrow pulse that rises in synchronization with the rise of the signals PL and P, and serves as a sample/hold command to the sample and hold circuit 31. Timing signal P2 is signal PL
, PR is a pulse with a predetermined width t that rises in synchronization with the falling of PR. The timing signal P3 is a narrow pulse that rises in synchronization with the fall of the timing signal P2, and the average value circuit 30 is reset at the rise of the timing signal P3.
Average value of welding current during the period t+ (=to ts) from the fall of the signal to the fall of the timing signal P
Calculate. timing signal P, is timing signal P,
This is a narrow pulse that rises in synchronization with the falling of , and serves as a sample/hold command for the sample and hold circuit SH in FIG. The timing signal P is a narrow pulse that rises in synchronization with the falling edge of the timing signal P4, and is a narrow pulse that rises in synchronization with the falling edge of the timing signal P4.
This becomes a hold command. The average value circuit 30 calculates the welding current average value ■AL for the period txt from the fall of the odd-numbered timing pulse P4 to the fall of the timing signal P, but this timing signal P6 is calculated as the odd-numbered timing signal pg. This pulse is generated synchronously, has the same pulse width as the timing signal Pt, and serves as a sample/hold command to the sample and hold circuit 42.

Further, the average value circuit 30 also outputs even-numbered timing pulses P,
The period t from the fall of the timing signal P7 to the fall of the timing signal P7
! This timing signal P7 is a pulse that is generated in synchronization with the even-order timing signal P, has the same pulse width as the timing signal P2, and has the same pulse width as the timing signal P2. This is a sample/hold command for the timing signal P
A is a narrow pulse that serves as an output command to the left/right shift discriminating circuit 46, and is generated in synchronization with an even odd-order timing pulse (the second period of the oscillation period) among the odd-order timing pulses P1. Note that 1o indicates the welding current (detected value) when the oscillation center is shifted toward the left end with respect to the left and right ends of the groove.

Prior to the start of welding, welding condition parameters are set by the operator. When welding (oscillation welding) is started, the welding current is detected through the current detector 17,
The detected welding current is passed through a low-pass filter 28 and an amplifier 2.
9 to the average value circuit 30. In the average value circuit 30, the above period 1. The welding current average value ■1 is calculated and output, and this welding current measurement value iAs is determined by the timing signal P.
1 and held in the sample hold circuit 31. After welding starts, the operator checks the welding condition parameters and readjusts each parameter if necessary. The welding speed setting value SKO is adjusted by an initial welding speed setting device 39. After the adjustment is completed, the operator issues a read command to the A/D conversion circuit 32 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 32 that receives this command reads the welding current measurement value I held by the sample hold circuit 31.
The AS is taken in, converted into a digital signal, and input to the D/A conversion circuit 33. The D/A conversion circuit 33 converts the input welding current measurement value ■□ into an analog value and holds it as a welding current reference value IAC until the end of welding. Thereafter, the welding current measurement values r and s detected every half period of the oscillation are compared with the welding current reference value IAc, and the welding current deviation ΔI is sent out from the differential amplifier circuit 34. This welding current deviation Δ
I is amplified through the dead zone circuit 35 and supplied to the deviation update processing circuit 36. The deviation update processing circuit 36 generates an additional value Δ obtained by adding the welding current deviation ΔIDH input this time through the dead zone circuit 35 to ΔIDN−1sU as described above.
I Create DNSLM. This added value ΔI DN3t1M of the welding current deviation is level-converted by the amplifier circuit 37 and becomes the welding speed deviation ΔSN. Truck drive motor 8 (
The servo amplifier 40 that drives the welding speed setting value 5
Addition value S+i++ of IIO and this welding speed deviation ΔS
In response to su, 4 as a welding speed command, the trolley drive motor 8
Control the speed of (Ml).

The average value circuit 30 oscillates welding 1 to 4 to the left end point of the oscillation pattern and stops, and then starts oscillating toward the right end point from the falling edge of timing pulse P4 until a further period t has elapsed. (until timing pulse P3 rises) Welding current average value IAL (left end side current average value) is calculated, and when welding 1-4 reaches the right end point of the oscillation pattern and stops, after stopping, welding current average value IAL (left end side current average value) The welding current average value IAR (right end side current average value) is calculated until the oscillation is started toward , and the period t has elapsed. The deviation ΔIAL-R between the left end side current average value IAL and the right end side current average value JAR is calculated by the differential amplifier 44 and inputted to the left/right positional deviation determination circuit 46. The left and right positional deviation determination circuit 46 detects the left and right end side current deviation ΔIA1. −
If R= (IAL IA, I) E3 > 0 (however, E3 is the dead band of the dead band circuit 45), it is determined that the center point of the oscillation pattern has shifted to the left, and a right shift command is sent to the servo amplifier 22. do. As a result, the servo amplifier 22 moves the left and right axis slider 11 to the right ~ ΔI
Since the drive motor 12 is driven to move by a distance corresponding to AL-11, the oscillation center of the oscillation device 13 is shifted to the center position between the open ends, and the deviation is corrected. Similarly, ΔIAL-R-(IAL
JAR) +E3<0, there is a shift to the right, so the left-right axis slider 11 is driven to the left, the oscillation center of the oscillation device 13 is shifted to the center position between the left and right weld lines, and the shift is corrected. −B, <ΔI At−*
<E3, the left-right axis slider 11 is not shifted. In this embodiment, the correction operation is performed every two oscillation periods using the timing pulse P8, but the correction period is not limited to this.

As described above, in this embodiment, the initially set welding speed setting value SKO is changed to the welding speed deviation Δ every oscillation half cycle.
Welding is performed while correcting with SN, and as shown in Fig. 5, the welding speed command value of the Nth oscillation half cycle is 5NSUN.
is the welding speed command value 5 of the N-1st oscillation half cycle
The sum of N-1-3UN and the signal value obtained by converting the current deviation ΔIDN, 1 generated in the N-1st oscillation half cycle into the welding current command signal level is the welding speed deviation ΔS.
This time (N-1st oscillator I)
・Only if the signal value obtained by converting the measured welding current deviation ΔIDN-1 into a welding speed command signal level increases or decreases with respect to the welding speed command value SSN-l5II, welding is performed by the speed corresponding to the increase or decrease. Speed command (a SN-131
114 is corrected. Therefore, as long as the groove width does not suddenly change discontinuously, the welding speed will faithfully follow the fluctuations in the groove width and will not change suddenly due to factors on the control device side, so the control operation will be It is stable and can always obtain a weld bead of the appropriate height.

In this embodiment, the current values used to determine the left-right position deviation are the left-end average current value IAL and the right-end average current value TAB, so even if arc instability occurs, its influence is sufficiently reduced, and the left-right position Since there is no large error in determining the deviation,
Accurate left-right tracing of the weld line can be achieved even under the outer weld line where the arc is unstable.

In addition, in this embodiment, the average value circuit 30 is commonly used to measure the welding current for welding speed control and to measure the welding current for left-right tracing control of the welding line. It has the advantage of being easier.

[Embodiment of the Second Invention] FIG. 6 shows an embodiment of the second invention, which differs from the embodiment of the first invention in that it has an oscillation width control function. In FIG. 6, 47 is an adder circuit which takes in the left end current average value IAL and the right end current average value TAR from sample and hold circuits 42 and 43, respectively, and calculates the sum of the left and right end currents'AL+R=I 4□+I
Calculate AR. 48 is an A/D conversion circuit, 49 is a D/A
A conversion circuit, both circuits include an A/D conversion circuit 32, D
It has the same function as the /A conversion circuit, and upon receiving the read command generated by the operator operation described above, converts the left and right end sum current IAL41 to the oscillation width reference current value I. This is provided for initial setting as C. Differential amplifier circuit 5
0 is the deviation Δ1. between IWC and IAL-R (hereinafter referred to as 1.). amplify. This deviation ΔIW is supplied to an oscillation width determination circuit 52 through a dead band circuit 51. The oscillation width determination circuit 52 sends an oscillation pattern correction command to the servo amplifier 24 according to the polarity and magnitude of the deviation ΔI8. The servo amplifier 24 is connected not only to an oscillation width setter 25, an oscillation period setter 26, and an oscillation width discrimination circuit 52, but also to a speed ratio discrimination circuit 54. This speed ratio discrimination circuit 54 has a speed ratio SX-ΔSN/SK calculated by the speed ratio calculation circuit 53.
O is guided. Both are provided to prevent the oscillation period from being excessive or insufficient relative to the welding speed, and to keep the oscillation period within an allowable range, as the oscillation period increases or decreases as the oscillation width is controlled to increase or decrease as described above. ing. The speed ratio discrimination circuit 54 has positive and negative three
It consists of a value comparator circuit, for example, O<S
X<0.3.0.3<S x<0.6,S,>
Discriminate between 6 and 6. Now, S++>(l, 0<3.<0.
In the case of 3, a command to maintain the oscillation speed at the initial setting speed (the speed set at the time of the above-mentioned reading command);
If 0.3<SX<0,6(7), 30% speed increase command,
In the case of S, λ0.6, a 60% speed increase command is sent to the servo amplifier 24. Conversely, when sX<0, Q<SX<0.3
If so, a set speed maintenance command is sent to the servo amplifier 24, if 0.3<SX<0.6, a 30% deceleration command is sent to the servo amplifier 24, and if 3X>0.6, a 60% deceleration command is sent to the servo amplifier 24. In the servo amplifier 24,
Upon receiving the above command from the speed ratio discrimination circuit 54, the corresponding speed pattern is selected. Although the other configurations are the same as those in FIG. 2, the same components are given the same reference numerals and their explanations will be omitted.

Above left and right end sum current■. changes in response to variations in the groove width, and the oscillation width reference current value I. It decreases when the groove width becomes wider than the oscillation width when C is set, and increases when the groove width becomes narrower than the oscillation width. The oscillation width determination circuit 52 determines the deviation ΔIw = Iwc I
, 1-E4 > 0 (however, E4 is the dead band of the dead band circuit 51), it is determined that the oscillation width is insufficient, an oscillation width expansion command is sent to the servo amplifier 24, and the deviation Δ1iy =' Iwc IH+E4 <'0
In this case, it is determined that the oscillation width is excessive, and an oscillation width reduction command is supplied to the servo amplifier 24. When the servo amplifier 24 receives the oscillation width enlargement or reduction command, it controls the drive motor 14 in a direction in which the oscillation amplitude is enlarged or reduced by the width corresponding to the deviation Δ+w. Of course, the amount of correction of the oscillation width may not be made proportional to the deviation Δ■, but may be made in proportion to a preset constant amount. Further, this oscillation rate correction operation may be performed every arbitrary period of the oscillation rate, for example, every two periods.

In this embodiment, the sum of the average current value on the left end side and the average value on the right end side is used as a parameter for determining whether the oscillation width of the welding torch is excessive or insufficient with respect to the groove width. This directly reflects the fluctuation of the groove width and is independent of the welding speed, so even if the welding conditions are changed for each layer in multi-layer build-up welding, the oscillation width control is There is no need to change the settings for the necessary conditions.

It should be noted that it is understood that the oscillation width can be controlled using the speed ratio SX-ΔSN/SKo as a parameter, and this speed ratio SX-ΔSN/5IIO
Since is a dimensionless value, it is possible to obtain the same effect as when the sum current 1w is used as a parameter.

〔Effect of the invention〕

As explained above, this invention allows the welding speed to faithfully follow fluctuations in the groove width, and also performs weld line tracing control using the average current value at the left and right ends of the oscillation as a parameter, making the arc unstable. Even under difficult conditions, it is possible to achieve more accurate and precise tracing control than conventional methods, improving welding quality.Furthermore, the oscillation width can be controlled to directly reflect groove width fluctuations. Since it is performed based on the parameters, especially in multi-layer welding,
This has a great practical effect because the conventionally troublesome work of changing control condition settings for each layer can be omitted.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a welding device embodying the present invention, FIG. 2 is a block diagram of a control device in the above embodiment, and FIG.
4 is a waveform time chart of the timing signal in the above embodiment. FIG. 5 is a diagram showing an example of a welding speed command pattern in the above embodiment. FIG. 7 is a block diagram showing another embodiment of the present invention, and FIG. 7 is a diagram showing an example of a welding speed command pattern in a conventional adaptive control method. 4-Welding torch, 13-Oscillating device, 19-Vertical positional deviation determination circuit, 30-Average value circuit, 31.42.43
-sample hold circuit, 32-A/D conversion circuit,
33-D/A conversion circuit, 34.44-differential amplifier,
35.45- Dead band circuit, 36- Deviation update processing circuit, 4
6-Right and left positional deviation discrimination circuit.

Claims (4)

[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 holding part of the welding torch and the surface of the workpiece, the above-mentioned welding is oscillated. The welding current within each oscillation half cycle of the torch is detected as a non-instantaneous value, and this welding current measurement value is initially set as the welding current reference value, and after the welding speed is initialized, it is measured every oscillation half cycle. The above welding current measurement value is compared with the above welding current reference value, the deviation is extracted, the deviation measured in the current oscillation half cycle is added to the deviation measured in the previous oscillation half cycle, and the deviation after addition is has increased or decreased with respect to the deviation measured in the previous oscillation half cycle, the welding speed command value for the current oscillation half cycle is corrected by the speed corresponding to the above increase/decrease, and the corrected welding is performed. The welding speed of the next half-cycle of oscillation is controlled by the speed command value, and the welding current average value in a predetermined section at one end and the other end of the welding torch is taken out, and the average value of both welding currents is calculated. A groove adaptive control method for consumable electrode type arc welding, characterized in that the oscillation center position of a welding torch is corrected at every predetermined oscillation cycle based on the deviation, and the left and right tracing of a welding line is performed. (2) A groove adaptive control method for consumable electrode arc welding according to claim 1, wherein the welding current measurement value is an average value over a predetermined period within an oscillation half cycle. (3) In consumable electrode arc welding, in which arc welding is performed while the welding torch is oscillated in the groove width direction while maintaining a constant distance between the holding part of the welding torch and the surface of the workpiece, the welding is oscillated. The welding current within each oscillation half cycle of the torch is detected as a non-instantaneous value, and this welding current measurement value is initially set as the welding current reference value, and after the welding speed is initialized, it is measured every oscillation half cycle. The above welding current measurement value is compared with the above welding current reference value, the deviation is extracted, the deviation measured in the current oscillation half cycle is added to the deviation measured in the previous oscillation half cycle, and the deviation after addition is has increased or decreased with respect to the deviation measured in the previous oscillation half cycle, the welding speed command value for the current oscillation half cycle is corrected by the speed corresponding to the above increase/decrease, and the corrected welding is performed. The welding speed of the next half-cycle of oscillation is controlled by the speed command value, and the welding current average value in a predetermined section at one end and the other end of the welding torch is taken out, and the average value of both welding currents is calculated. The oscillation center position of the welding torch is corrected at each predetermined oscillation cycle based on the deviation.The welding line is traced left and right, and on the other hand, after initially setting the sum of the above two welding current average values as the oscillation width current reference value, the oscillation A consumable electrode characterized in that the sum of the average values of both welding currents measured every cycle is compared with the oscillation width current reference value, and the oscillation width is increased or decreased every predetermined oscillation cycle in response to the deviation. A groove adaptive control method for arc welding. (4) The groove adaptive control method for consumable electrode arc welding according to claim 3, wherein the welding current measurement value is an average value over a predetermined period within an oscillation half cycle.