JPS62179870A - Automatic adjusting method for filler wire inserting position of automatic arc welding machine - Google Patents

Abstract

PURPOSE:To eliminate an influence of welding conditions of a wire feed quantity and a welding current, etc., and to adjust a position of a filler wire to a correct position, by detecting a variation of an arc voltage generated by a shift to a wire inserting position, and adjusting automatically the wire inserting position to a prescribed position. CONSTITUTION:When a prescribed voltage is applied between a non-consumable electrode 1 and a base metal 2, an arc is generated, and a filler wire 4a is inserted into this arc, by which welding is executed. In this case, an arc voltage which has been detected by an arc voltage detector 3 is smoothed through a switch 9, and thereafter, applied to a feed nozzle driving signal generator 12, compared with a reference voltage therein, based on which a feed nozzle driving signal is applied to a driving circuit 14. In accordance with a variation of an arc voltage, an inserting position of the filler wire 4a is controlled, and the filler wire 4a is maintained automatically in an optimum position.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for controlling the position of a filler wire in non-consumable electrode automatic arc welding.

[Conventional technology]

In so-called TIG welding, in which arc welding is performed using a tungsten wire in an inert gas, it is necessary to adjust the insertion position of the filler wire due to filler wear and the like.

For example, Japanese Patent Laid-Open No. 48-6953 discloses a method for automatically adjusting the inserting position of a filler wire. This uses the fact that the voltage generated between the filler wire and the base metal changes due to changes in the position of the filler wire and the electrode (arc), and this voltage becomes the voltage that occurs when the wire is inserted at the correct position. In this method, the filler wire position adjustment motor is rotated to move the filler wire in the vertical direction, and the filler wire insertion position is automatically adjusted to an appropriate position.

[Problem that the invention seeks to solve]

In the above conventional technology, (a) the voltage between the filler wire and the base metal is determined not only by the filler wire insertion position but also by the welding conditions such as the filler wire feeding speed, welding current, and voltage, the protruding length of the wire, and the wear of the depth. Since the welding conditions vary depending on the angle, etc., it is necessary to change the welding conditions and insertion position depending on the posture, especially in all-position welding of pipes, etc., which is characterized by complicated correction.

(b) It has the disadvantage that it cannot be used when passing current through a wire such as pot wire TI'G.

The present invention was made to solve the problems of the conventional technology, and eliminates the influence of welding conditions such as wire feed rate and welding current, and is suitable for hot wire TIG welding where current is passed through filler wire. It is an object of the present invention to provide a method that can be applied to the filler wire and automatically adjust the position of the filler wire to an appropriate position without requiring complicated correction.

[Means to solve the problem]

The method for automatically adjusting the insertion position of a filler wire according to the present invention is a method for automatically adjusting the insertion position of a filler wire in non-consumable electrode type automatic arc welding, in which filler wire is supplied and welding is performed while automatically controlling the arc length by constant arc voltage control. The feature is that the filler wire insertion position is automatically adjusted to a predetermined position by detecting fluctuations in the arc voltage generated by the process.

[Effect]

This method was developed based on the fact that the arc voltage fluctuates due to misalignment of the filler wire, and the wire insertion position is automatically adjusted to the appropriate position using this fluctuation in the arc voltage.

〔Example〕

Figure 4 shows the variation in arc voltage when the filler wire insertion position was changed.

In (a), when the filler wire 4a is inserted into the arc 52 and close to the electrode 1 and the welding torch 4 is oscillated, the number of arc voltage fluctuations is 10 to 10 per second in all parts of the oscillation width. The ratio is 20 times. Note that 55 is a weld bead and 56 is a molten boule.

In (b), the filler wire 4a is inserted into the arc but is further away from the electrode than in (a), and the arc fluctuates at a rate of 2 to 10 times per second.

(C) shows a case where the welding boule 56 and the filler wire 4a are inserted, but the arc voltage fluctuates only at both ends of the oscillation when it is close to the boundary with the arc 52, and the number of fluctuations is 1 to 2 per second. This is the percentage of times.

(d) shows the case where the filler wire 4a is inserted into the end of the melting boule 56 (the fluctuations as in a3 to (c) are not observed).

In this way, the position of the filler wire can be controlled by using the relationship between the number of changes in the arc voltage and the position of the filler wire.

In addition, the amplitude when the arc voltage fluctuates is 05 to 2 V larger than when there is no fluctuation, and it tends to increase as the wire approaches the electrode, so it is also possible to detect and control this amplitude change. be.

Although the present invention can control the wire position by continuously detecting fluctuations in the arc voltage during oscillation operation, it is also possible to control the wire position by sampling the arc voltage in synchronization with the on-rate operation. Although it has been widely used for oscillated welding, the same tendency can be obtained for straight welding, so it can be used in the same manner as for oscillated welding.

[Embodiment 1] In this embodiment, fluctuations in arc voltage are continuously detected and continuously controlled. As shown in Fig. 1, when overlay welding is performed on the base metal 2 without a groove with the filler wire 4a in a downward position, the oscillation width is wide and the oscillation speed is relatively slow. As there is no groove wall at the oscillating end, there is no big difference in the state of the melt pool at any part of the oscillating operation. Therefore, the influence of delays in the arc voltage signal and operation is small, and even if fluctuations in the arc voltage are continuously detected and wire position control is performed, hunting does not occur and good welding can be performed.

[Embodiment 2] Welding is carried out in two passes in one layer within the groove 13 of the base material 2 by oscillating the filler wire and the electrode as shown in FIG. In this case, the appropriate position of the filler wire changes in each part of the oscillation.

If this is controlled continuously, a hunting phenomenon is likely to occur. To prevent this, it is preferable to control the wire insertion position by sampling the welding voltage at the center of the oscillate or at the end of the oscillate where the groove wall exists in synchronization with the oscillation operation. Furthermore, if the on-rate stop period is short or the oscillation width is small, arc voltage fluctuations may occur during the oscillation stop time or a little later than when the oscillation is in operation. In such a case, it can be detected sufficiently by adding a delay to the sampling time. The sampling delay time is preferably about 100 m5ec.

FIG. 3 shows a configuration diagram of an apparatus for implementing Examples 1 and 2. With this device, it is possible to control by detecting the number of fluctuations in the arc voltage or by detecting the amplitude of the arc voltage, and it is only necessary to decide which one to extract as a signal.

In Fig. 3, l is a non-consumable electrode, 2 is a base material to be welded, and 3 is a non-consumable electrode.
is an arc voltage detection device, and 4 is a filler wire feeding nozzle. 5 is a constant arc length control device, 6 is a driver that drives a motor 7 that feeds the non-consumable electrode 1 in response to a signal from the constant arc length control device 5, and 8 is a machine that drives a welding torch 21 consisting of a rack and pinion etc. Each element 5 to 8 realizes a known constant arc control device.

9 is a switch for timing sampling in the second embodiment; IO is a commercial frequency of 50 to 60 Hz;
A bandpass filter that removes arc voltage noise due to oscillation below Hz and passes signals of about 5 to 20 Hz, 1
Reference numeral 1 denotes a smoothing device that converts the signal from the bandpass filter 10 into a DC level.

12 is a wire feed nozzle drive direction signal generator that compares the signal from the reference level setter 13 and the signal from the smoothing device 11, and if the difference exceeds a dead band of a certain width set internally, the wire feed nozzle drive direction signal generator Generates a feed nozzle drive direction signal. A wire feed nozzle drive circuit 14 receives a signal from the drive signal generator 12 and drives the feed nozzle drive motor 17 through a driver 16 by the amount of movement set by the movement amount setter 15. 18 is a mechanical transmission element that drives the wire feeding nozzle 4. 19 and 20 are circuits for executing the second embodiment, and 19 is a sampling signal generator which generates a signal a indicating the position of the oscillation axis (both ends stopped or moving).
A sampling command signal is created from a signal from a selector 20 that selects whether to use the method of the first embodiment or the method of the second embodiment, and generates a sampling signal for opening and closing the switch 9.

When welding according to the first embodiment shown in FIG. 1 is performed in the above-described circuit, no signal is generated from the sampling signal generator 19, and the switch 9 is continuously turned on.

When a predetermined voltage is applied between the non-consumable electrode 1 and the base material 2 from a power supply device (not shown), an arc is generated, and the filler wire 4a is inserted into this arc to perform welding. At this time, the arc voltage detected by the arc voltage detector 3 is applied to the filter 10 via the switch 9, smoothed by the smoothing device 11, and applied to the feed nozzle drive signal generator 12. This signal generator 12
Then, when the difference between the reference voltage set by the reference level setter 13 and the detected arc voltage exceeds a predetermined dead zone, a feed nozzle drive signal is output.

This feeding nozzle drive signal is applied to the drive circuit 14, converted into a signal having a magnitude corresponding to the value set by the movement amount setter 15, and applied to the driver 16. The driver 16 rotates the feed motor 17 according to the magnitude of the signal applied from the drive circuit 14, controls the amount of filler wire 4a output from the nozzle 4, and controls the base material of the filler wire 4a in the arc. Controls the insertion position for 3.

Through the above-described operation, the inserting position of the filler wire is controlled according to changes in the arc voltage, and the filler wire is maintained at an optimal position. In the case shown in the second embodiment, the switch 9 is turned on by the sampling signal output from the sampling signal generator 19 when the non-consumable electrode comes to the on-rate end where the groove wall exists, and the switch 9 is turned off otherwise. Become.

As a result, the output signal of the arc voltage detector 3 is the non-consumable electrode l.
The signal is sampled in synchronization with the oscillation rate of , and applied to the filter 10 .

Therefore, the feed nozzle drive signal generator 12 outputs a feed nozzle drive signal based on the arc voltage applied at the sampling time, and the insertion position of the filler wire 4a is adjusted to the arc voltage by the same operation as described above. controlled accordingly.

[Example 3] In this example, sampling is performed at the center of the oscillation and during the stop period at both ends. When the groove angle is small as shown in Figure 5, the arc voltage opens when the torch approaches the groove wall. The voltage becomes the voltage with the front wall, and the voltage with the pool in the center of the oscillator. For this reason, the arc voltage is kept constant by an automatic voltage control device, so the voltage is almost constant, but the distance to the pool changes. For this reason, the situation as shown in FIG. 4(c) is likely to occur. This embodiment uses this phenomenon to perform control, and the fluctuation of the arc voltage at the oscillation end is 1 to 2.
The arc voltage is controlled so that fluctuations do not occur while the torch is moving by oscillation and oscillation. If the wire is close to the electrode, fluctuations in the arc voltage will be detected even while the torch is moving due to the on-rate; if the wire is far from the electrode, fluctuations in the arc voltage will not occur even when the oscillation is stopped. Therefore, it is possible to judge whether the wire is close at the center of the oscillation, or whether the wire is far away when the oscillation is stopped.

FIG. 6 is a block diagram of an apparatus for carrying out the third embodiment, and the same parts as in FIG. 3 are given the same numbers.

In the figure, 30 is a signal generator that generates the signal ASB of FIG. 7 synchronized with the oscillation rate from the signal a, and the two contacts 31a and 31b are opened and closed by the signals A and B, respectively. 34
is a device that moves the wire feed nozzle in the direction closer to the electrode, and when the signal from 31a becomes less than the signal from the reference signal generator 33, the wire feed nozzle moves by the amount of movement set by the movement amount setting device 34. A signal generator that generates a signal.
638 that generates signal C is a device that moves the wire feeding nozzle in the direction away from the electrode, and when the signal from 31b exceeds the signal from the reference signal generator 37, the electrode movement is set by the movement amount setting device 39. A signal generator generates a signal for moving the wire feeding nozzle by the amount of the wire feeding nozzle. 40 is a priority encoder that prioritizes signals C and D, and ignores signal C immediately after signal failure occurs and the nozzle is separated from the electrode.

In the above example, it is synchronized with the oscillation signal, but if the oscillation stop time at both ends is short, a delay of about 100 m5ec may be provided in the signal generator 30.

〔Effect of the invention〕

As described in detail above, according to the present invention, the wire insertion position can be easily controlled without being affected by welding conditions such as the wire feeding speed and the wire protrusion length. Its control is also easy to handle because it does not require complicated correction.

In addition, even when the filler wire is inserted into the arc, it can be used in a short-circuited state to the pool, and by performing sampling control, the most suitable control method can be selected when performing oscillation welding, so it has a wide range of applications. There are advantages.

[Brief explanation of drawings]

FIG. 1 is a front view showing one embodiment of the present invention, FIG. 2 is a front view showing a second embodiment, FIG. 3 is a block diagram showing a circuit of a control device used in the above embodiment, and FIG. Figure 4 is a diagram showing the position of the filler wire and arc voltage, Figure 5 is a front view showing the third embodiment, Figure 6 is a block diagram showing the circuit used in the third embodiment, and Figure 7. 7 is a waveform diagram showing signal waveforms of main parts of the circuit of FIG. 6. FIG.

Claims (1)

[Claims] (1) In non-consumable electrode type automatic arc welding, which automatically controls the arc length using constant arc voltage control and performs welding by supplying filler wire, fluctuations in the arc voltage that occur due to misalignment of the wire insertion position are detected. A method for automatically adjusting a filler wire insertion position, the method comprising automatically adjusting the insertion position to a predetermined position.