DE2357196A1 - Pulsed arc welding power system - with thyristor shunting smoothing choke - Google Patents

Abstract

The welding current for a pulped arc welding plant is shaped by a rectifier and a choke to level out current pulsations. A thyristor is arranged in parallel to the choke and bypasses this choke is a selected pulsation period of the rectified voltage with a delay. This requires only one source of supply and eliminates the dips in the basic current curve after a pulse has passed. Current, pulse amplitude, and pulse duration can be adjusted separately within the wide limits. The weight, dimensions and cost are much reduced (by 50-80%).

Description

Dipl.-lng, Dr. jur.

Frank Arnold Nix

P-.i ₅ -: ', nwalt OO C Π 1 QC

Frankfurt am Main 70 ■ " ^{O / N}

Ie 123

EHTMCHQTdHG FOR THE FORMING OF THE BOW STROLE AT LICHTBOGEIi-IISHJLSSCIIWElSSEM "

The invention relates to the field of arc welding, in particular to a device for forming of arc currents in pulse arc welding.

At present, devices are used for pulse arc welding which contain two supply sources and zxvar a basic current source and an impulse current source, the operated in parallel with a common load (the arc).

A direct current generator is usually used as the basic power source or a rectifier is used to maintain a smooth direct current.

Either a DC 509821/0512 is used as the pulse current source

ORIGINAL! MSPECTED

rich tor in pulse mode or a feed source that s Mode of operation - based on the discharge of a previously charged capacity via a controlled valve and via the arc .

The disadvantage of such devices are their large size Dimensions and their by the presence of two Inefficiency caused by food sources. In addition, the base current source is due to the passage of current pulses of a voltage increase in the arc partially or completely blocked, with the basic current curve after the pulse passage Has depressions.

These dips in the base current curve can occur at small values of the basic current to disturb the stability of the arc burning when welding materials with low thickness lead.

It is also a rectifier circuit with pulsating rectified voltage is known, in which one at the G-Ie rectifier output to smooth pulsations of the rectified current Smoothing choke located in the circuit of the rectified current is used (see e.g. I.L. Kaganow "Power converters with electron and ion devices", GEI, Moscow, 1956).

This rectifier cannot be used in the known embodiment for pulse arc welding.

The present invention aims to remedy the above-mentioned deficiencies.

The invention is based on the object of a device

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device for forming the arc current be in the arc pulse to develop welding, which is only a source of food Contains supply of basic current and pulse current and the Dips in the characteristic curve of the output current eliminated.

This object is achieved in that the device for forming the arc current during arc pulse welding, one rectifier and one at the rectifier output contains lying and for smoothing pulsations of the rectified current serving choke, according to the invention is equipped with a controlled valve which is parallel to the throttle mentioned and in a selected pulsation period of the rectified voltage, said choke with a delay in relation to the beginning, the pulsation period the rectified voltage bridged.

The device for formation can expediently dos Bogenstrcries in pulse arc welding with additional controlled valves can be fitted to the Input of the rectifier can be switched and give the opportunity to simultaneously with the bridging of the mentioned Choke the rectified pulsating voltage in the remaining time of the pulsation period of the rectified Increase tension.

Ss is' -iucli appropriate to the control electrodes of the mentioned additional controlled valves a delay element to r.u close, the rectified pulsating Spaiaiui *; -; with a delay in relation to the time

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BATH ORIGINAL

is increased by bridging the aforementioned throttle.

The device designed according to the invention for forming the arc current in pulse arc welding is
characterized by the following advantages: 1) Absence of
Dips in the eogen current curve after impulse sag, with the stability of the welding process and the quality
the formation of mowing can be increased; 2) separate regulation of the
Main parameters of the welding process (the basic current strength, the pulse amplitude and the pulse duration) within wide limits; 2) Reduction in weight, dimensions and
Cost (around 50 to 80 $ S) as well as improvement in operating conditions; 4) the possibility of extensive use of arc pulse welding of various types of steel and non-ferrous metals, especially with a smaller thickness of 1
up to 3 mh with the help of melting electrodes.

The invention is illustrated in the following detailed description of its exemplary embodiments with reference to FIG the accompanying drawings explained in more detail. Here show:

Fig. 1 is an electrical circuit diagram of the device
for forming the arc current in the arc-pulse welding according to the invention (first variant);

2 shows an electrical circuit diagram of the device for forming the arc current in pulse arc welding according to the invention (second variant) .;

3 shows an electrical circuit diagram of the device for the 509821/0512

"O * 3 Ε» "7 1 Q ß

Formation of the arc flow during arc welding according to the invention (third variant);

4 shows the course of the rectified pulsating voltage;

Fig. 5 total current curve;

Fig. 6 Course of the rectified pulsating voltage at the same time when the rectifier voltage increases with dex * throttle bridging by a controlled valve;

Fig. 7 Total current curve when the rectifier voltage is increased at the same time as the throttle bridging by a controlled valve;

Fig. 8 Course of the rectified pulsating voltage when the rectifier voltage increases, there is a delay in relation to the point in time at which the throttle is bridged will;

Fig. 9 Total current curve when increasing the rectifier voltage with. Delay in relation to the timing of the throttle override.

Fig. 10 is an electrical circuit diagram of the device for Formation of the arc current during arc pulse welding (the most popular variant).

The device for the formation of the arc current at Arc pulse welding contains a rectifier 1 (Fig. 1) with a Fetz transformer 2, which has a primary · winding 3 u ^ ä a secondary winding 4 with zero point tap having. The beginnings of windings 3 and 4 are marked with dots in Fig. 1. The rectification takes place by means of non-controlled valves 5 and -6. So that is

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-6-

Rectifier after the single-phase rectifier circuit liullpunkt built. At the output of the rectifier 1 is located a smoothing throttle 7, which is used to smooth pulsations of the rectified current. Parallel to the smoothing throttle 7 a controllable valve is connected, which represents an ÖMayristor 8 .. On the Steuoranschluss .9 des Thyristor 8 control pulses are given by a control circuit 10. For the control circuit 10, any known circuit of the control pulse source with a phase shifter to be used. The load, the role of which the welding arc plays, is a resistor connected in series 11 and a back emf (of an element 12) and connected to the output of the rectifier 1.

The second variant of the device for forming the arc current shown in FIG. 2 during arc pulse welding contains essentially the same elements as the device according to FIG. 1. The functions of the rectification and the regulation are separate. The rectification takes place as in the first variant by non-controlled valves 5 and 6, but effect the phase control the controlled valves (thyristors) 13 and 14, which are connected in parallel with each other and at the beginning of the primary winding 3 lie. The primary winding 3 has a tap which enables the transformation factor of the transformer 2 to be changed in stages. The gradual change

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the translation factor for the purpose of increasing the number of equal courts

th voltage "cause the controlled valves (hyristors) 15 and 16, which are parallel to each other and also parallel to the thyristors 13 and 14 and with the tap of the primary winding 3 are connected. The control connections I7 and

18 of the thyristors I3 and 14 and the control connections I9 and 20 of the thyristors I5 and 16 are connected to the control circuit 10 connected.

The third variant of the device for forming the arc current in arc pulse welding differs differs from the described second variant in that between the control circuit 10 and the control connections

19 and 20 of the thyristors 15 and 16 are a delay element

21 is switched on. In the fourth variant of the device, thyristors are used to relieve the diodes 5 and 6 (FIG. 10)

22 and 23 of smaller power applied, each of which the choke coil 7 together with the diodes 5 and 6 of the corre

chanden phase bridged. The momentum component flows through it of the current diodes 5 and 6 do not.

The device for forming the arc current in pulse arc welding works as follows.

As long as the thyristor 8 (Fig. 3) is blocked, flows in the welding circuit under the effect of the pulsating voltage U (FIG. 4) a direct current smoothed by the choke 7. With a given inductance of the choke 7 and with selected load plan providers, the current strength of the The opening phase of the thyristors I3 and 14 is determined. When applying a pulse supplied by the control circuit 10 to the control terminal 9 of the thyristor 8 becomes the latter opened and bypasses the throttle 7 with a delay in relation to the beginning of the pulsation period of the rectified Voltage U ". As a result, the welding current

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circle under the effect of the rectified by the rectifier 1 pulsating voltage U (Fig. 4) formed into a current pulse i (FIr ₃ · 5).

In bridging the throttle 7 (I 3 ^p ig.) By the

Thyristor 8 flows through the latter a current difference, that of the pulse current and of a free energy output the Drosoel 7 via the circuit choke 7, thyristor 8 generated electricity is formed. The attenuation in this one The current circuit is very small, and that of the choke 7 The supplied current changes during the initiation of the pulse current practically not, whereby it remains the same as the basic current magnitude before the impulse passage. At the end of the pulsation period of the voltage from the rectifier 1, the current difference flowing through the thyristor 8 is equal to Hull, v.'obei the thyristor 8 blocks, and the r flows through the load the choke 7 maintained basic current.

The current pulse repetition frequency iiän / ΐΐ from the frequency the throttle bridging by the thyristor 8 al) and is the. Pulsation frequency equal to the rectified voltage or an integer part of this frequency.

The amplitude and the duration of the pulse depend on the operating phase of the thyristor bridging the choke 7 8 with respect to the start of pulsation of the rectified voltage dependent.

In order to obtain larger amplitudes of the current impulses at low values of the basic current, the pulsating Voltage of the rectifier 1 simultaneously with the Ü

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Bridging of the IL-rossel 7 by the thyristor 8 by opening the thyristors 15 or 16 by means of the pulses supplied by the control circuit 10 is increased. In this case, a voltage of opposite polarity appears at the thyristors 13 or 14, which blocks these thyristors. Under the effect of the increased rectified pulsating voltage U (FIG. 6), a current pulse i (FIG. 7) with a large amplitude is formed.

The regulation of the amplitude and the duration of the Stroraimpulses takes place independently of its duration by switching on the supply element 21 (Fig. 3). The throttle 7 is bridged by applying a pulse from the control circuit to the control port 9 of the thyristor 8, as described above, whereupon with a delay in relation to the time of the throttle bridging, which is caused when the pulse passes through the delay element 21 is, the thyristor 15 is opened and thereby the rectified pulsating voltage U (Fig. 8) is higher. Value reached. When the increased pulsating voltage U (Fig. 8) acts, the current pulse i (Fig. 9) is formed in the welding circuit

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Claims (1)

-10-PAl ¹ ELf ^r üAi; 'S2? HÜ CIiE '' IJ device for the formation of the Eogenstromes uein arc pulse welding, which has a rectifier and a rectifier at the. Rectifier output and r.ur üläi; Young of puloations of the rectified current contains throttle, marked ennzeiclinot dur ο Ii a controlled valve that runs parallel to the elected Throttle (7) is located and in a selected one. Pulsat -'- j.onsporiode to the equal tension the equalized thrush (7) with a delay in relation to the beginning of the pulsation period the rectified voltage, bridged. 2ο establishment '/ λχχ Formieruiii :; des. 3ogenstroKiec in LichtlDOgen pulse welding according to claim 1, ge Ic e 11 η draws et by additional controlled valves that are connected to the input of the rectifier (1) and give the possibility of bridging at the same time with the bridging; of the aforementioned choke (7) increase the rectified pulsating voltage in the remaining time of the pulsation period of the rectified voltage eu. 3, device for the formation of the arc current during arc pulse welding according to claims 1 and 2, thereby ge lc e η η ζ e _># leans that the control (I9, 20) of the mentioned additional ^ oatourten. Valves hlü '/ tl ^ »l6) a delay element (21) is switched on, and as a result the rectified pulsating voltage is increased with a delay in relation to the point in time at which the aforementioned throttle (7) is bypassed, 509821/0512 • Μ. Blank page