JPS6025228B2 - Arc welding equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an arc welding device in which the transient current suppression characteristics of an inductive reactor inserted in a welding current output circuit are improved.

Recently, an electrode wire is continuously fed toward the base metal while shielding carbon dioxide gas, so that an arc is generated between the tip of the electrode wire and the base metal, and the electrode wire is
A so-called short-circuit transfer type C02 arc welding method has been developed and is widely used, in which a short circuit is periodically made to the base material at a rate of about 00 times/second, and metal transfer occurs during the short circuit.

This welding method is particularly effective for welding thin base materials because the arc is not continuous, so the base metal will not be excessively heated and holes will not form or the weld metal will melt. By the way, when such a welding method is performed using a normal arc welding power source, an excessive short-circuit current flows due to a short circuit, resulting in significant welding spatter, and the so-called arc is extremely hard, making it difficult to perform welding work smoothly. The welding result is also not favorable.

As a means of solving this problem, it is possible to insert an appropriate inductance, that is, an inductive reactor, in series with the welding current output circuit to delay the rise speed of the short circuit current, thereby limiting the peak value of the short circuit current. Are known.

However, a suitably large short-circuit current is required to break the short-circuit state, so if the inductance value of the inductive reactor is too large, the short-circuit state may persist and no arc will occur, or the number of short-circuits may be reduced, resulting in efficient melting. There is a problem that heating cannot be carried out, and if the inductance value of the inductive reactor is too small, the peak value of the short circuit current becomes high and there is a problem that the occurrence of welding spatter increases. For this reason, an inductive reactor with a main winding and an auxiliary winding wound around an iron core is used, the main winding is inserted into the welding current output circuit, and the auxiliary winding is magnetically coupled to the main winding. Connect a variable resistor and operate the variable resistor to increase the current flowing through the main winding.
It is also being considered to make the attenuation at an appropriate speed.

However, even if it is possible to suppress the peak value of the welding current by controlling the magnetic coupling between the main winding and the auxiliary winding using a variable resistor, a certain amount of resistance is still present in the inductive reactor due to the variable resistor. Since it is included from the beginning, the impedance is high as a whole, and the welding current increases due to the vector sum of resistance and inductance from the beginning of a short circuit, so the response of the welding current at the time of a short circuit, that is, the rising slope becomes poor. It has not been put into practical use because the arc is unstable. This is because, in ideal arc welding, the moment a short circuit occurs, the welding current rapidly rises to a level that generates an arc, ensuring the generation of the arc, and then suppressing the rise of the welding current and causing the welding droplets to form due to the pinch effect. It is desired that the droplets be raised at a gentle gradient toward before the peak until they are transferred, so that the transfer of the droplets is performed smoothly without spatter. Furthermore, as will be explained in detail later, the rising slope of the welding current depends on the inductance and resistance of the circuit, and the vector sum of the rising slope determined by the inductance and the rising slope determined by the resistance is the actual rising slope of the welding current. Become. Therefore, immediately after a short circuit, the inductive reactor acts rather like a pure resistance, and the smaller the resistance value, the more 1=V
As is clear from the relationship /R, the welding current rises rapidly and can be said to have a large current value. For example, when considering a practical welding device with an applied voltage of 20 V and a welding current of about 130 A (peak value 200 A) near the arc generation point, the most appropriate resistance value is between 0.10 and 0.20. It is. However, in the above-mentioned auxiliary winding method, since the variable resistance is included in the transfer reactor from the beginning, it is difficult to suppress the resistance value at the time of a short circuit to a small value such as the above 0.10 to 0.20. be. In other words, the auxiliary winding method does not have the idea of making the inductive reactor act as a pure resistor immediately after a short circuit, but increases the welding current (pulling up) to the arc generation level to mainly reduce the inductance of the bulk inductive reactor. As a result, the rising slope of the welding current becomes gentle, making arc generation unstable. Furthermore, the inductive reactor has a complicated configuration in which a main winding and approximately the same number of auxiliary windings are wound around the iron core, and a large variable resistor with a large current capacity must be used, making the device complex and Because it was large and expensive, it could not be used as a regular, especially general-purpose, arc welding device. For this reason, the concession reactors currently widely used in general-purpose arc welding apparatuses are generally of the open magnetic path type, for example, those in which a type 1 iron core is wound.

In reality, a plurality of intermediate taps are provided in order to set the inductance value, and after assembly is completed, the intermediate taps are selectively connected to bring the inductance close to an appropriate value. However, since this type of iron core uses an open magnetic path type, it has the advantage of being able to be made smaller without the risk of magnetic saturation, but on the other hand, the inductance value is unstable and therefore requires adjustment during assembly work. This is troublesome, and the inductance changes depending on the presence or absence of magnetic material around the device, resulting in unstable operation during use. This invention was made in view of these circumstances, and the inductive reactor to be used is a small one with a simple structure similar to that of a conventional open magnetic path iron core wound with wires, and can be used as a general-purpose type. In addition, it is possible to maintain the arc in a so-called soft state, increase the number of short circuits, reduce the occurrence of welding spatter, and achieve an extremely stable arc start that can be performed instantaneously without mistakes. The present invention provides an arc welding device that can perform welding work.

Embodiments of the present invention will be described below with reference to the drawings.

A welding wire 2 is continuously fed toward the base material 1 by a wire feeding mechanism 3 through a power feeding tip 4.

Then, the negative output terminal of the DC arc welding power source 5 is directly connected to the base metal 1 via the inductive reactor 6 in series, and the positive output terminal is connected to the power supply tip 4, and between the base metal 1 and the welding wire 2. The arc voltage is supplied and the welding current is applied. Note that the DC arc welding power source 5 adjusts, for example, a three-phase AC voltage with a sliding transformer,
The adjusted voltage is rectified by a three-phase rectifier and then output, making it a DC constant voltage power supply with low internal impedance and low output voltage.

The inductive reactor 6 includes a winding 8 wound around an open magnetic path iron core 7, and a compensation ring 9 made of a band-shaped conductor made of a highly conductive material such as aluminum or copper placed around the central part of the winding 8. The winding 8 is insulated from the winding 8, and the winding 8 is insulated from the winding 8.

The compensation ring 9 overlaps both ends of the strip conductor and bolts,
It was mechanically connected across the Nhatto River. With such a configuration, the rising slope of the welding current, the restriction of the peak value, and the subsequent falling slope of the post-melting current can be freely selected and improved by the compensation ring 9. That is, in short-circuit transition arc welding, a period in which the base metal and the wire are short-circuited, and an arc period in which the short-circuit is resolved and an arc is generated between the base metal and the welding wire are alternately repeated. However, the welding current in this short-circuit transition region is ideally
Like the waveform shown in the figure, it is best to have a waveform that rises rapidly at the start of a short circuit to generate an arc, then gradually rises until the transfer of droplets due to the pinch effect, and then quickly decreases toward the 0 point. If the voltage rises rapidly, arcing is certain to occur.

On the other hand, as described above, the rising slope of the welding current depends on the inductance and resistance in the circuit, and the substantial rising slope of the welding current is determined by the vector sum of the inductance and resistance. In other words, at the time of a short circuit, the more the induced IJ factor acts as a pure resistance, the steeper the rising slope will be, and as the resistance value increases to 4, the welding current will suddenly reach the arc generation level point b due to the relationship 1=V/R. Rise. The compensating ring 9 of the inductive reactor 6 configured as described above is momentarily linked to the magnetic flux of the winding 8 when short-circuited, and generates heat due to the induced current flowing due to the induced voltage.

In other words, the compensation ring 9 functions as a resistance circuit connected in parallel with the inductance of the winding 8 inserted in series with the welding current output circuit in terms of an equivalent circuit. Also, the compensation ring 9 is connected to the winding 8
The degree of linkage with the magnetic flux differs depending on the position relative to the magnetic flux. For example, if it is located approximately at the center in the longitudinal direction of the winding as shown in FIG. 2, it interlinks with the total magnetic flux, and the moment the inductive reactor 6 is short-circuited, it acts as a pure resistance and almost no inductance acts. On the other hand, if the compensation ring 9 is brought closer to the end of the winding 8, its function as a pure resistance becomes smaller and its function as an inductance increases. Therefore, if the position of the compensation ring 9 is selected so that the resistance value that makes the rise of the welding current appropriate every time the welding wire 2 contacts the base metal 1 is selected,
As shown in FIG. 4, the arc can be instantaneously raised from point a to point b, and arc generation can be ensured each time. The inductive reactor 6 acts as a pure resistor, and then the compensation ring 9 connects the input side of the winding 8 with the compensation ring 9 in order to push back the magnetic flux in an attempt to block the current flowing through the winding 8. A leakage magnetic flux is generated between the compensation ring 9 and the output side, and an inductance is generated there, and the vector sum of this inductance and resistance causes the welding current to flow from point b to point c as shown in Figure 4. Raise at a gentle angle to avoid spatter. Therefore, the transfer of the droplets due to the pin effect is performed smoothly without spatter. The magnitude of the inductance due to the leakage magnetic flux is determined by the position of the compensation ring 9.

That is, if the compensation ring 9 is located at the center of the winding 8 in FIG. 8A, the number of turns on the left and right sides of the compensation ring 9 is the same. Since the magnitude of the inductance is proportional to the two cases of the number of turns, it becomes a value proportional to N20N2. On the other hand, if the compensating ring 9 is moved to the edge as shown in FIG. And for both of them, (N')20n
Since 2>N20N2, the former has a smaller inductance. In this way, the position of the compensation ring 9 is selected in consideration of its function as a pure resistance immediately after a short circuit and its subsequent function as an inductance component. In addition, as shown in Figure 4, the welding voltage rises at the peak value of the welding current, that is, at point c, and then tries to settle down to a no-load voltage (voltage at which the arc does not continue). 8 is superimposed, causing a gradual drop as shown by the broken line, and it takes time to reach the no-load voltage, during which time the arc is maintained.

Therefore, the welding current also falls slowly from point c. However, in the inductive reactor configured as described above, the energy accumulated in the winding 8 is absorbed and consumed as heat by the compensation ring 9, and as a result, the superposition of nitrogen energy on the welding voltage is eliminated, and the welding voltage quickly settles down to the no-load voltage, and correspondingly, the welding current attenuates at a steep angle from point c to prepare for the next short circuit transition, thereby increasing the number of short circuits within a unit time. Therefore, with this device, short circuits can be reliably broken, especially since the current rises rapidly to the arc generation level, and short circuits can be broken in a relatively short time, and the peak value of the current is appropriately limited, so welding spatter can be prevented. In other words, a stable arc with a small number of arcs can be obtained, and a very large number of short-circuit transitions, which has been difficult to achieve with conventional devices, can be easily and stably achieved.

FIG. 5 shows a recorded waveform of a welding current in a conventional semi-automatic C02 arc welding device using an induction IJ vector in which a 31-turn wire is wound around a type 1 iron core. Figure 6 shows the recorded waveform of welding current in a semi-automatic C02 arc welding device according to the present invention, which uses an induction reactor in which a 31-turn winding is wound around a type 1 iron pole and a compensation ring is wound around the outside of the inductive reactor. This shows that.

In addition, in both Figures 5 and 6, the welding current value is 15 ships, and 1
．． The welding current when using a 2 sail ◇ welding wire was recorded on a recording paper running at 50 skins/sec.

As is clear from the comparison between Figures 5 and 6, the device of this invention can increase the number of short-circuit transitions compared to the conventional device, and also reduces the occurrence of welding spatter. Stable welding can be performed.

This is not limited to the case where the welding current is 15 ships, but also applies when the welding current value is changed.

FIG. 7 shows the relationship between the welding current value and the number of short-circuit transitions, where the dotted line shows the case of the conventional device, and the solid line shows the case of the present invention device. As is clear from this figure, the number of short-circuit transitions in the device according to the present invention is significantly increased over the range from low current to high current, compared to the conventional device. Moreover, the number of short-circuit transitions that can be achieved by the device of this invention is something that would be difficult to achieve with a secondary device, and in this respect, the device of this invention exhibits an extremely superior function that cannot be obtained with the conventional device. It's something you get. According to experiments, the most desirable characteristics are obtained when the ampere-turn due to the current flowing through the compensation ring is set to 300 to 200 MT when the welding current is 150 A, and more preferably 600 to 1000 AT. It has been found that the following results can be obtained.

In addition, it was found that by adjusting the winding of the compensation ring around the winding and moving it in all directions of the axis of the open magnetic path type iron'○, the interlinkage state of the magnetic flux with respect to the compensation ring can be adjusted and the characteristics can be adjusted. ing.

As is clear from the above, according to the present invention, a winding is wound around an open magnetic path type iron core as an inductive reactor, and a compensating ring made of a good conductive material is insulated and wound around the outer periphery of the winding. Since a small device is used, the configuration is almost the same as the general-purpose device of the auxiliary, and in terms of an equivalent circuit, the main winding and auxiliary winding are wound around the iron core, and the auxiliary winding is It is almost the same as using an inductive reactor with a resistor connected, so it is a small and simple device that is almost the same as a conventional general-purpose device.
It is possible to provide an arc welding device that exhibits extremely superior functions that cannot be obtained with conventional general-purpose devices.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of the present invention, Fig. 2 is an enlarged front view showing an inductive IJ vector of the same embodiment, with a portion cut away, Fig. 3 is a side view, and Fig. 4 5 is a diagram showing a model of the welding voltage waveform and welding current waveform in the same example, FIG. 5 is a waveform record diagram of the molten acid current in the subordinate device, and FIG. 6 is a waveform record diagram of the welding current in the device of the present invention. , FIG. 7 is a characteristic diagram showing the relationship between the number of short-circuit transitions and the welding current, and FIG. 1. ... Base material, 2 ... Electrode wire, 3.
...Wire feeding mechanism, 4...Power feeding chip, 5
....DC arc welding power source, 6..Induction reactor, 7.. Iron core, 8.. Winding wire, 9.. Compensation ring. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] 1. A winding is wound around an open magnetic path iron core, and around the outer circumference of the winding,
An inductive reactor is provided in which a compensating ring made of a highly conductive material that can be moved in the longitudinal direction of the winding is wound insulated from the above winding, and the winding of this inductive reactor is connected to the welding current output circuit of a DC arc welding power source. An arc welding device characterized by being inserted in series with.