JPH064192B2 - Arc welding control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention sets an output set value, an actual command value to a welding machine body when an output commensurate with the output set value is obtained, and a feed back value which is an output detected value at this time to 1 The present invention relates to an arc welding control device of a type that stores a set of data, reads a command value corresponding to a required output set value from the data stored previously during welding, and supplies the command value to the main body of the welding machine.

Conventional technology Generally, in arc welding equipment, output current value, voltage value,
The welding speed and the like are set, and the output value is fed back to the set value to form a closed loop to obtain a required value. However, in such a feed back control system, if the welding method, welding equipment, material, etc. applied is changed, the actual output value will change variously even for the same set position of the output setter, and the same value will be obtained. Therefore, it was not possible to attach the correct direct reading scale to the output setting device. For example, in the consumable electrode type arc welding method using a power source with a constant pressure characteristic, the electrode wire is fed at a substantially constant speed, and since the welding current is proportional to this wire feeding speed, the wire feeding is a signal for setting the welding current. Specify the feed rate. By maintaining the wire feeding speed at the set value, a welding current having a value of "wire feeding amount = wire melting amount" flows. In this way, the welding current is determined by the wire feed rate, so if the wire material and diameter are changed, the current required for the same amount of melting will of course change, so that even for the same feed rate, a completely different An electric current will flow. Furthermore, even if these external factors are the same, the welding power source and wire feed rate are not constant because the output fluctuation rate is not constant depending on the output value. However, the welding current has different values.

Furthermore, when supplying the output setting signal from another device such as a large welding device or a robot for welding in which the output setting device and the welding machine main body such as the welding power source and wire feeding device are installed separately, the setting device is set. It is necessary that the output signals of the above and the signals that can be accepted by the welder body that is the controlled object are exactly the same, and when the types of these signals are different, as well as when the types are the same. Also, if the level is different due to the difference in rated capacity, etc., a completely irrelevant output is generated. For this reason, in these large-sized welding devices and welding robots, the welding power source and wire feeding device to be combined with these are limited to specific ones, and there is almost no degree of freedom in equipment configuration. .

As a solution to the above problems, the present inventor manually adjusts the command value until the actual output matches the output value set in the output setting value, and then sets the setting value and the actual command value at this time. Is provided as a set of data, and at the time of actual welding, the previously stored data for the output required value set by the output setter is read and the corresponding command value is set to the welding machine main body. Then, the main body of the welding machine uses this output command value as an input signal and proposes an arc welding control device of a system in which feed back control is performed so that an output corresponding to the input signal can be obtained. With this method, the input / output characteristics of the welder main body can be stored in the control device by teaching operation in advance, so if the configuration of the welder main body to be combined is determined, the output set value and actual output value You get a good match. However, even in this device, the torch position during welding changes due to the change of the worker, and even if the worker is the same, due to camera shake or the step of the workpiece, the welding torch and the surface of the workpiece are welded. When the distance between and changes and the arc length or the protruding length of the wire from the welding torch changes, the output that is set may not be obtained.

For example, consider a case where a welding power source with a constant voltage is used to feed a wire at a constant speed corresponding to a specified output current value.

When the output current and the output voltage are respectively set as (I _w , E _w ), the command value (I _r ,
E _r ) is read out and supplied to the wire feeder and the welding power source, respectively. The welding power source controls the feed back by itself so that the output voltage becomes a value corresponding to the command voltage in response to the command value E _r , while the wire feeding device receives the command value I _r and the wire feeding / feeding motor. Is controlled, and feedback control is performed so that the speed becomes a value corresponding to the command value. At this time, if the distance between the welding torch and the object to be welded is equal to the distance when the data was previously stored, the arc voltage and the welding current at that time are reproduced and the set output is obtained. However, if the distance between the welding torch and the work piece is different from the value when the data was stored, the original arc voltage and welding current values cannot be obtained even if the same output voltage and wire feeding speed are reproduced. become. Now, suppose that the surface of the workpiece is suddenly lowered and the distance between the welding torch and the workpiece is increased. This change in distance initially appears as a change in arc length. For this reason, the arc voltage tries to increase by the length of the arc length, but this is restricted by the welding power source to the set value, and the welding current greatly decreases along the voltage-current characteristic curve of the welding power source. It will be. During this time, since the wire is fed at a constant speed, the amount of melting of the wire is reduced by the amount by which the welding current is reduced, which increases the protruding length of the wire from the welding torch. The arc length is reduced by the increase in the wire protrusion length. For this reason, the arc voltage gradually decreases and, conversely, the welding current begins to increase. On the other hand, when the wire protrusion length increases, the amount of heat generated by the wire's specific resistance increases due to the current flowing through this protrusion, and the increase in welding current due to the decrease in arc voltage and the amount of heat generated by the increase in wire protrusion length When the melting amount of the wire, which is determined by the sum of the increments and the wire feeding speed, reaches a new equilibrium state and stabilizes. At this time, the wire protrusion length, the welding current, and the arc voltage are all different from the values at the time of storing the data, and as a result, the output command value I
Despite the original values of _r and E _r , the expected output was not obtained, and the electric power input to the arc column = (arc voltage) ×
(Welding current) will change. For this reason, the melting amount of the wire does not change, but the range of melting the work piece,
That is, the amount of penetration changes, and a predetermined welding result cannot be obtained. A similar phenomenon occurs also in the case of a method of controlling the wire feeding speed by the arc voltage using a constant current power source. In this case, the wire protrusion length changes due to the change in the distance between the welding torch and the work piece, and the arc voltage changes in accordance with the change in the voltage drop that occurs at this protruding portion. Will result. Therefore, in any case, the specified output cannot be obtained,
The effect of the method of storing data in advance was halved by experiments.

SUMMARY OF THE INVENTION According to the present invention, first, as a teaching operation, a reproduction output setter is set to a predetermined scale position, and a teaching output setter that actually supplies a reference signal for output setting to a welding device is manually operated. When the output value equal to the setting scale of the playback output setting device is obtained by adjusting, the output value of the teaching output setting device at this time is used as the actual output command value, and the playback output at this time is adjusted. Repeatedly storing the combination with the output signal of the setter for the scales of the plurality of output setters for reproduction, and when performing actual welding, select the desired value with the output setter for reproduction, In the regenerative arc welding control device, which stores the output command value corresponding to the selected value, determines the actual output command value by taking out the value directly or calculated from the data stored in advance and the data to be stored. Then, in addition to the output set value and the output command value, the feedback value at the time of normal output is stored as one set of data, and at the time of playback, the stored feedback value and the actual feedback value are compared and the difference is reduced. The value is corrected, and if this correction amount exceeds a certain value or if there is a difference more than a certain amount between the read feedback value and the actual feedback value, it is judged as an alarm and the output is stopped. According to the present invention, welding is performed at a torch height different from that at the time of teaching, regardless of changes in various welding conditions and welders to be combined, according to the present invention. Even if you go, you can always get the output as set value, and if you cannot follow the set value due to a failure of the feedback system, take measures such as alarm and output stop. Is obtained by adapted to prevented the defective welding Te.

Embodiment FIG. 1 is a connection diagram showing an embodiment of the arc welding control device of the present invention. The figure shows an example in which the present invention is applied to an apparatus of a system in which the welding current is controlled by the feed rate of the consumable electrode wire and the welding voltage is controlled by the output voltage of the welding power source. In the figure, reference numeral 1 is a welding power source, and in the embodiment shown in the figure, a power source having a substantially constant voltage characteristic with adjustable output voltage is used. Reference numeral 2 denotes an electric motor control unit for controlling the feeding speed of the consumable electrode wire 6 (hereinafter simply referred to as a wire), which controls the rotation speed of the electric motor 3 according to the welding current setting signal. Reference numeral 4 denotes a wire feeding roll connected to the electric motor 3, and 5 denotes an object to be welded. The output of the welding power source 1 is supplied to the wire 6 and the object to be welded 5. Reference numeral 7 denotes a welding current detecting section which detects the welding current by using a shunt resistor, a DC current transformer or the like, and detects the average value of the welding current through an appropriate smoothing circuit, a low pass filter or the like. A welding voltage detector 8 detects the voltage between the wire 6 and the object to be welded 5 and obtains an averaged output like the current detector 7. Reference numeral 9 is a teaching output setting device for manual adjustment. In the case of the embodiment shown in FIG.
R1 and welding voltage teaching setter VR2. 10
Is a reproduction output setting device, for example, a digital switch such as a thumb rotary switch is used, and a welding current reproduction setting device 101 and a welding voltage reproduction setting device 10 are used.
2 and outputs a digital signal or a voltage signal. When the teaching output setter 9 is manually adjusted at the time of teaching, and the outputs obtained by the current detector 7 and the voltage detector 8 are equal to the set values of the reproduction output setter 10, respectively, The output signals I _r and E _r of the teaching output setting device 9 at this time are used as output command values, and the reproducing output setting device 10 is used.
Outputs I _w and E _w and the feedback signal at that time,
That is, it is an actual data storage unit that stores the output of the current detection unit 7 and the output of the voltage detection unit 8 as a set of data (I _r , I _w , I _o ), (E _r , E _w , E _o ). , 12 are combinations of two output set values adjacent to each other among the data stored in the actual data storage unit 11, the output command value and the feedback back value, for example, I _r1 , I _w1 , I _o1 and I _r2 , I _w2 , I _o2. From these, the intermediate output command value is calculated by linear approximation for each appropriate pitch ΔI _W of the output current, and the approximation data, that is, I _w1 + nΔ
Approximate data calculation unit for calculating command value I _r1 + nΔI _r and feed back value I _o1 + n ΔI _o corresponding to I _w , and 13 is an approximate data storage unit for storing output data of the approximate data calculation unit 12. The output data of the actual data storage unit 11 and the approximate data obtained by calculating the data of the intermediate position between them are stored together. Reference numeral 14 designates the output value of the teaching output setting device 9 as an output command value at the time of teaching, and the corresponding output of the reproducing output setting device 10 and both outputs of the current detecting portion 7 and the voltage detecting portion 8 together with the actual data storage portion 11
When the set value of the output setter 10 for reproduction is designated at the time of reproduction, the output command value and the feed back value corresponding to the set value are read from the approximate data storage unit 13 for reproduction. Reference numeral 15 denotes a display unit, which receives the output of the approximate data storage unit 13 and the outputs of the current detection unit 7 and the voltage detection unit 8 as input, and feeds the feedback signal I out of the outputs read from the approximate data storage unit 13 before the start of welding. _A switching circuit 151 for switching the input signals so as to display _o and E _o and display the outputs I _a and E _a of each detection unit during welding and a display 152 for displaying the result. Reference numeral 16 denotes a mode switching switch for switching between teaching and reproduction, so that each output of the teaching output setting device 9 is directly supplied to the welding power source 1 and the wire feeding / feeding motive control unit 2 which are the welding machine main body only at the time of teaching. The mode of the storage / reproduction control unit 14 is switched. Reference numeral 17 indicates the teaching output setting device 9 when the teaching output setting device 9 is adjusted at the time of teaching to confirm that the output current and the output current match the set value of the reproduction output setting device 10 on the display unit 15. A combination of the output, the output of the output setting device for reproduction 10 and the feedback value at that time, I _r , I _w ,
A push button switch for inputting a command signal for storing I _o and E _r , E _w , and E _o in the actual data storage unit 11. Reference numeral 18 denotes a comparator 181 and an output current command value correction unit 1
An output current command value correcting means composed of 82, and 19 a comparator 1
91 is an output voltage command value correction unit including an output voltage command value correction unit 192.

The operation of the embodiment shown in FIG. 1 will be described with reference to the explanatory view of FIG.

At the beginning of the combination of the main body of the welding machine and the control device, there is no data in the actual output command value storage unit 11, and accordingly, there is no data stored in the approximate output command value storage unit 13 either. Switch 16 teach side (T side)
As a result, the work of teaching the command value for obtaining the required output value to the device is performed. The procedure for teaching the output current with the output voltage fixed will be described with reference to FIGS. 2 (a) to 2 (c).
First, teach the point of Fig. 2 (a). The current setting device 101 of the reproduction output setting device 10 is set to the minimum output value I of the welding machine body.
Set to _w1 . Further, the reproduction voltage setting device 102 is also set to the minimum output value E _w1 . In this state, test welding is performed, and the current setting device VR1 and the voltage setting device VR2 of the teaching output setting device 9 are manually operated to display the design values I _w1 and E _{w1 of the} reproducing output setting device 10 on the display unit 15. Adjust to match. With this adjustment obtained, pushbutton switch 17
By pressing, the set value I _w1 corresponding to that of FIG. 2 (a),
The E _w1 , the command values I _r11 and E _r11, and the feed back values I _o1 and E _o1 are stored in the actual data storage unit 11 as one set of data. Next, the setting of the reproducing output voltage setting device 102 is set to E _{w1 as} it is, and the setting of the reproducing current setting device 101 corresponds to the position of FIG. 2 (a) which corresponds approximately to the maximum output current of the welding machine main body. Change to _w2 and test weld again. Even during this test welding, the teaching output setting device 9
To operate the setting device VR1 and VR2 to the display I _a and E _a of the display unit 15 manually is equal to the set value I _w2 and E _w1, respectively, the push Botansuitsuchi 17 at a predetermined output is obtained When _pressed , the output (I _w2 , E _w1 , I _r21 , E _r21 , I _o2 , E _o1 ) of each setter at that time is stored in the actual data storage unit 11 as a set of data corresponding to those in FIG. At this time, since the data corresponding to the previously stored data is stored in the actual data storage unit 11, the approximate data calculation unit 12 causes the two adjacent sets of data (I _w1 ,
E _w1 , I _r11 , E _r11 , I _o1 , E _o1 ) and (I _w2 , E _w1 , I
_r21 , E _r21 , I _o2 , E _o1 ) and the data in the middle part between them are all assumed to be on a straight line connecting between FIG. set value is calculated for each appropriate peach △ I _w of I _w, approximating the calculated result as data for the output voltage E _w1 data storage unit 1
Store in 3. Of course, the definite actual data located between them differs depending on the output characteristics of the welding machine body, and these are not always in direct proportion, but these become correct values as the number of teaching points increases, as will be described later. Since it approaches, it is not necessary to perform complicated curve approximation or function calculation. The calculation pitch will be determined according to the capacity of the welder body and the storage unit. Normally, if the output voltage is set at 1 V to 2 V intervals and the output current is set at about 2 A to 5 A, the actual welding conditions can be selected. On the other hand, sufficient accuracy can be guaranteed.

Next, the output current and output voltage corresponding to those in FIG. 2 (b) are set to I _w3 and E _w1 by the reproduction output setting device 10, and the teaching output setting device 9 is operated in the same manner as above. Obtain the required command values I _r31 , E _r31 and feed back values I _o3 , E _o1 . Data corresponding to this (I _w3 , E _w1 , I _r31 , E
_r31 , I _o3 , E _o1 ) is stored in the actual data storage unit 11, and − and − intermediate data are adjacent (I _w1 , E _w1 , I _r11 , E _r11 , I _o1 , E _o1 ) and ( I _w3 , E _w1 , I _r31 , E _r31 , I _o3 , E _o1 ) and (I
_w3 , E _w1 , I _r31 , E _r31 , I _o3 , E _o1 ) and (I _w2 ,
E _w1 , I _r21 , E _r21 , E _o21 , I _o2 , E _o1 ) is calculated by the approximate data calculation unit 12 at the same pitch _{ΔI w} as before, and the approximate data storage unit 1 is calculated according to the calculation result.
The data of 3 is updated. As a result, the data on the broken line shown by the solid line in FIG. 2B is stored in the approximate data storage unit 13. If the same work is repeated for other output current set values I _w , detailed output current set values I _w and output command values I _r , E _{r when the} output voltage set value is E _w1 .
And the relationship between the feed back values I _o and E _o can be obtained as shown in FIG. 2 (c). Further, if the above-mentioned device is repeatedly executed for different output voltage set values E _w , the output command values E _r , I _r and the feed back value I corresponding to the respective combinations of the output voltage set values E _w and the output current set values I _w. A combination of _o and E _o is obtained. In this case, since the input / output characteristic of the output detector is likely to be linear in the feed back value, the feed back value with respect to the set value changes substantially linearly as shown in FIG. Since the same feedback back value should be obtained even if the element of is changed, the feedback back value becomes a set value for each set value, and the result is as shown in Table 1.

An example of the calculation progress of the approximate data calculation unit 12 for the data obtained from the results of these teaching operations is as follows.

To simplify the explanation, actual output command values for the minimum value (I _w1 , E _w1 ) and maximum value (I _wn , E _wm ) of the current setting device 101 and the voltage setting device 102 of the reproduction output setting device 10, respectively. And the feedback value are (I _r11 , E _r11 , I _o1 , E _o1 ), (I _rn1 , E _rn1 ,
_Let us consider the case where it is obtained as four-point data of I _on , E _o1 ), (I _r1m , E _r1m , I _o1 , E _om ) and (I _rnm , E _rnm , I _on , E _om ).

As the calculation pitch, the output current is equally divided into x parts, and the output voltage is equally divided into y parts. If the four actual data are linearly changed, the output current setting value I _w (I _{wn -I w1) / x = △} I output current command value to the variation of _w I _r is _{(I rn1 -I r11) / x} = △ I rx output voltage command value E _r is _(E rnm -E _r1m) / x = △ E _rx output current fed back value I _o is _{(I on -I o1) / x} = △ I o only changed, the output voltage fed back value E _o is not to any change with respect to change in the output current Become.

Further, the output voltage command value E _r is (E _r1m -E _r11 ) / y = ΔE _ry output current command value in response to the change of (E _wm −E _w1 ) / y = ΔE _w of the output voltage set value E _w I _r is (I _rnm −I _rn1 ) / y = ΔI _{ry The} output voltage feed back value E _o changes by (E _om −E _o1 ) / y = ΔI _o , and the output current feed back value changes with the output voltage change. On the other hand, nothing will change. _Therefore , I _wij and E _{wij in} Table 2 are the data (I _rij ,
E _rij , I _oi , E _oj ) is I _rij = I _r11 + i · _{ΔI rx} + j · _{ΔI ry} E _rij = E _r11 + i · ΔE _rx + j · ΔE _ry I _oi = I _o1 + i · ΔI _o A combination of E _oj = E _o1 + _{jΔE o} (where o ≦ i ≦ x and o ≦ j ≦ y) should be calculated and stored as approximate data. Usually, these data do not undergo extreme changes and are gentle curves that are slightly apart from linear changes, so the data to be taught are the minimum and maximum values of current and voltage, and several intermediate points between them. Sufficient accuracy can be obtained only by teaching.

At the time of actual welding, the mode switching switch 16 is regenerated (P
Side), the teaching output setting device 9 is disabled, and the output current command value correction unit 18 and the output voltage command unit 19 are enabled. In this state, when the reproduction output setter 10 is set to a required value and welding is started, the storage / reproduction control unit 14 reads the corresponding output command value from the approximate data storage unit 13. At this time, if the response speeds of the command value correction means 18 and 19 are made sufficiently slower than the response speeds of the welding power source 1 and the motor control unit 2, the command values I _r and E _r read from the approximate data storage unit 13 will be described. Is transmitted as it is to the welding power source 1 and the electric motor control unit 2. Upon receipt of this command value, the welding power source 1 and the electric motor control unit 2 carry out publicly known feed back control so that the output voltage and the wire feeding speed become values corresponding to the command signal. The output value at this time is detected by the output current detector 7 and the output voltage detector 8, and the detected values I _a and E _a are stored in the approximate data storage unit 1.
The normal feed back values I _o and E _o read out from No. 3 are compared by the comparators 181 and 191 of the correction means 18 and 19, and if there is a difference, the sign thereof is the command value correction unit 182 or 19.
2 is supplied. When the input signal is other than zero, the command value correction units 182 and 192 add or subtract the correction amounts ΔI _r and ΔE _r with a constant width to the command value in the direction of decreasing the difference depending on the sign of the input signal. _r ± ΔI _r = I _r ′, E _r ± ΔI _r =
It is sent to the electric motor control circuit 2 and the welding power source 1 as E _r ′. The electric motor controller 2 and the welding power source 1 change their outputs in response to the new command value. As a result, if the output values I _a and E _a do not become equal to the normal feedback values I _o and E _o , a further one-step correction operation is performed,
When they coincide with each other, equilibrium is reached, and the electric motor control unit 2 and the welding power source 1 continue to operate according to the respective corrected command values. When this equilibrium state continues for a certain period of time, the corrected command values I _r ′ and E _r ′ at this time are returned to the storage / reproduction control circuit 14 as correct command values, and the data in the actual data storage unit 11 is updated. In addition, the data in the approximate data storage unit 13 is also recalculated and updated accordingly. The correction interval needs to be set sufficiently longer than the response time of the motor control unit 2 and the welding power source 1.

As a result of the operation of the apparatus of FIG. 1 as described above, the protruding length of the wire from the welding torch changes due to the change of operator or the change in the distance between the workpiece and the welding torch as described above. Thus, even when the welding current or the welding voltage changes, the command value is automatically corrected so that the correct output can be obtained, so that the set output can always be obtained.

By the way, in the embodiment shown in FIG. 1, when the distance between the welding torch and the object to be welded is extremely changed, or the feed back control system is broken, a contact failure or a constant change is caused, the detected value is proportional to the output value. Even when the value is no longer obtained, the command value may be forcibly corrected and an unexpected output state may occur. For example, when the distance between the welding torch and the work piece becomes extremely large, the output current extremely decreases, and the correction means increases the wire feeding speed to compensate for this. In this way, the output value is restored to the specified value, but at this time, the welding voltage and welding current are equal to the set values, so the amount of penetration on the side of the work piece can be the specified value. Since the feeding speed is too much higher than the normal value, the amount of welding is extremely increased, so that a satisfactory welding result cannot be obtained. Further, when a failure occurs in the feedback system, a predetermined output cannot be obtained as a matter of course, and in any case, when the correction amount becomes too large, it is necessary to detect this and take an appropriate action.

FIG. 3 is a connection diagram showing another embodiment of the apparatus of the present invention for detecting this abnormal state. The embodiment shown in FIG. 10 is similar to the embodiment shown in FIG.
2, current command value correction abnormality determination means 20 including a comparator 203, a latch circuit 204, and an alarm device 205 such as an indicator light
And subtractor 211, reference setting device 212, comparator 213,
The voltage command value correction abnormality determining means 21 including a latch circuit 214 and an alarm device 215 is added. Also the first
Instead of the actual data storage unit 11 and the approximate data storage unit 13 shown in the embodiment shown in the figure, a data storage unit 22 integrating these is provided. The operation in the teaching stage and the reproducing operation in the normal state of the embodiment of FIG. 11 are the same as those of the embodiment of FIG. 1, but the actual data fetched by the teaching is stored in the data storage unit 22 and the approximate data calculation unit. The result calculated in 12 is returned to the data storage unit 22 and stored as approximate data together with the actual data. Therefore, the actual data obtained during teaching and the approximate data obtained by calculation are the actual data and the approximate data among the already stored data when another actual data obtained by the teaching is input next. Since it is necessary to distinguish between and, a symbol indicating these types is attached to each. In addition to the above, this storage unit stores only the actual data obtained by the teaching, and the actual data stored when the output current and the output voltage are designated by the output setting device during reproduction. It is also possible to read the actual data on both sides of this specified value closest to this specified value and calculate the output command value each time by proportional calculation, and in this case also the approximate calculation itself is a simple proportional calculation The time for does not matter so it is practical enough.

In the embodiment shown in FIG. 3, the command values I _r and E _r are appropriately corrected at the time of regeneration, that is, during actual welding, as in the embodiment shown in FIG. The command values I _r and E _r read at this time
And the specified values I _r ′ and E _r ′ after correction, respectively, are current command value correction abnormality determining means 20 and voltage command value abnormality determining means 2, respectively.
Input to 1. In the current command value correction abnormality determining means 20, the corrected command value I _r ′ is subtracted from the command value I _r read by the subtracter 201, and the difference (I _r −
I _r ′) is compared with the output of the reference setter 202 in the comparator 203. When the output of the subtractor 201 becomes larger than the set value of the reference setter 202, the latch circuit 204 holds this state, operates the alarm device 205 as a correction abnormality, notifies the operator, and outputs an output stop signal as necessary. Occurs and stops welding. Similarly, the output voltage command value correction amount abnormality determining means 21 detects when the correction amount of the output voltage command value is larger than the set value, and also detects this when the output voltage command value correction amount abnormality is held by the latch circuit to warn and stop welding if necessary. Take action.

According to the embodiment shown in the same figure, even if the height of the welding torch becomes abnormal or a failure occurs in the feedback control system, the welding is not continued without being defective, and especially the feedback feedback signal is broken. This eliminates the risk that the control system will runaway to the maximum output and the device will be destroyed if it is not returned.

In the embodiment shown in FIG. 3, when the difference between the previously stored command value and the corrected command value exceeds a predetermined value, this is detected to prevent an abnormal output from occurring. However, this command value correcting means needs to slow the response speed in order to operate the system stably, and it is necessary to make the cycle sufficiently long when the correction is performed at a constant time interval. Therefore, even if an abnormality occurs in the feed back system and the feed back value changes drastically, the output of the correction circuit itself gradually changes. During this time, due to the difference between the welding power supply and motor control circuit feed back value and the command value to be corrected and corrected, it operates to follow the command value at its own fast response speed. Therefore, even if the actual output changes improperly due to the occurrence of an abnormality, a considerable time delay occurs until the abnormality is detected. If an abnormality in the feedback system is an extreme one such as a wire break in the feedback output, the feedback power signal will be zero, and the welding power supply and motor control circuit will rapidly increase their output and reach their maximum output. . For this reason, an abnormal output is generated, and there is a risk of causing a large failure in each device. Therefore, it may be insufficient to provide the determination means as shown in the embodiment of FIG.

FIG. 4 is a connection diagram showing an embodiment in which the above points are improved. In addition to the embodiment shown in FIG. 3, the correction amount of the command value correction circuit shown in FIG. First to do
In addition to the determining means 20 and 21, the read feedback value (I _o , E _o ) and the actual feedback value (I _a ,
Monitoring the difference between E _a), which is provided with second determination means 23, 24 for determining the abnormality when coming certain amount or more. The second judging means 23, 24 are the same as the first judging means 20, 21 except that the input signals are different from the first judging means 20, 21, and therefore the details are omitted.
In the embodiment shown in FIG. 4, unlike the embodiment shown in FIG. 3, an actual data storage unit 11 similar to that shown in the embodiment shown in FIG. When the set values I _w and E _w are specified at the time of reproduction, the two data close to the specified values I _w and E _w specified by the instruction from the storage / reproduction control section 14 are stored in the actual data storage section 11.
From the data, and the approximate command values I _r and E _r and the approximate feed back values I _o and E _{o are} calculated from these data by proportional calculation.
To calculate. When the approximate data is calculated from the actual data every time the output set value is designated in this way, the capacity of the data storage unit can be made small. In the embodiment of the figure, as the second determination means,
By setting the reference value of the difference for judging the abnormality as a value larger than the reference value in the first judging means, the second judging means responds to a rapid and large change,
The first determining means responds to a relatively small change. Therefore, it is possible to detect the abnormality reliably in all cases.

In each of the above embodiments, as the command value correction unit,
The difference between the normal feedback value and the actual feedback value at fixed time intervals is explained by correcting the command value stepwise by a fixed amount by the sign of the signal. A method in which the value obtained by adding the signal itself to the read command value is set as the target value and the command value is corrected so as to approach the target value with a constant time constant may be used. Further, as the welding method to be applied, besides the one described in the embodiment, a welding power source having a constant current characteristic is used, and the wire feeding speed is controlled corresponding to the welding voltage to maintain a constant welding voltage. Alternatively, as the electrode, a non-consumable electrode such as tungsten may be used in addition to the consumable wire to control the position of the welding torch so that the welding voltage is constant. In any of these cases, the output current command value is supplied to the welding power source, and the output voltage command value is supplied as the wire feed speed command signal or the welding torch position command signal, respectively.

In addition, each part of each of the above-described embodiments is configured by using a specific circuit as illustrated, and all or part of them is the same as the function described in each embodiment by using a microprocessor. It is also possible to change each of the functions of the above so as to be implemented by a program.

Effects of the Invention In the present invention as described above, at the time of teaching, the output set value and the actual output command value are combined to simultaneously store the feed back value at the time of normal output, and at the time of reproduction, the actual output value and the read back back value are stored. Since the command value is automatically corrected so that the difference decreases in comparison, the welding voltage and welding current are adjusted even when the distance between the welding torch and the work piece changes during teaching and during playback. Since it is automatically corrected to the set value, it is possible to always maintain the welding conditions as planned. Also, when the external conditions change too much, the correction amount becomes too large due to disconnection, poor contact in the feedback control system, or aging of constants, or the feedback value is too far from the value obtained from the stored data. In this case, since a circuit for detecting this is provided, even when it is applied to an automatic welding apparatus, it is possible to prevent the defective product from being sent out by continuing the welding out of the set conditions, which facilitates unmanned operation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a connection diagram showing an embodiment of the present invention, and FIGS. 2 (a) to 2 (c) are diagrams for explaining the operation of the apparatus of the embodiment of FIG. 3 and 4 are connection diagrams showing another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 ... Welding power source, 2 ... Electric motor control part, 7 ... Welding current detection part, 8 ... Welding voltage detection part, 9 ... Teaching output setting device, 10
... reproduction output setting device, 11 ... actual data storage unit, 12 ... approximate data calculation unit, 13 ... approximate data storage unit, 14 ... storage / playback control unit, 15 ... display unit, 16 ... mode switching switch, 17 ... push button Switch, 18 ... Output current command value correction means, 19 ... Output voltage command value correction means, 20 ... Current command value correction amount abnormality determination means (first determination means), 21 ... Voltage command value correction amount abnormality determination means (first 1 determination means), 22
... Data storage unit, 23, 24 ... Second judging means.

Claims (4)

[Claims] 1. An output set value, a required command value corresponding to the output set value, and a feed back value at the time of normal output of the welding machine body when the command value is received are stored as one set of data, and welding is performed. In the arc welding control device of the method of reading the command value corresponding to the required output setting value from the stored data at the time and supplying it to the main body of the welding machine,
An arc welding control device provided with command value correcting means for comparing a normal feedback value and a feedback value corresponding to the read command value and correcting the command value in a direction in which the difference decreases. 2. A command value and a normal feed back value corresponding to the output set value at the time of welding are values calculated by proportional calculation from previously stored (set value, command value, feed back value) data. The arc welding control device according to claim 1. 3. An output set value, a required command value corresponding to the output set value, and a feed back value at the time of normal output of the welding machine body when the command value is received are stored as one set of data, and welding is performed. In the arc welding control device of the method of reading the command value corresponding to the required output setting value from the stored data at the time and supplying it to the main body of the welding machine,
A command value correction means for comparing the normal feedback value and the actual feedback value corresponding to the read command value and correcting the command value in the direction in which the difference decreases, and the correction amount of the command value correcting means is constant. An arc welding control device provided with a judging means for judging an abnormality and outputting at least one of an alarm and an output stop command when the amount exceeds the amount. 4. An output set value, a required command value corresponding to this output set value, and a feed back value at the time of normal output of the welding machine body when the command value is received are stored as one set of data, and welding is performed. In the arc welding control device of the method of reading the command value corresponding to the required output setting value from the stored data at the time and supplying it to the main body of the welding machine,
A command value correction means for comparing the normal feedback value and the actual feedback value corresponding to the read command value and correcting the command value in the direction in which the difference decreases, and the correction amount of the command value correcting means is constant. When the amount is equal to or more than the predetermined amount, the first judging means for judging an abnormality and outputting at least one of the alarm and the output stop command is compared with the normal feedback value and the actual feedback value, and the difference is a certain amount or more. An arc welding control device provided with a second determination means for determining an abnormality and outputting at least one of an alarm and an output stop command when it is hit.