SU1346366A1 - Apparatus for exciting and stabilizing the arcing of welded arc - Google Patents

Abstract

This invention relates to a welding technique. The aim of the invention is to reduce the level of radio interference, as well as to increase the efficiency of excitation. days and stabilization of the welding arc. To achieve the goal, a device containing an input transformer, a thyristor switch, a resistor, a diode, a capacitor, a high-voltage pulse generation unit and a protective capacitor, is additionally equipped with diodes, capacitors and resistors. Separate capacitors in one half-cycle of the mains voltage are charged through the diodes to the amplitude value of the secondary voltage of the input transformer. When the thyristor switch is triggered, the capacitors are discharged into the arc gap through resistors with different time constants, providing a pulse shape close to the trapezoid. One of the capacitors is discharged through a high voltage pulse generation unit. Therefore, two pulses, high-voltage and low-voltage, are simultaneously applied to the arc gap. This ensures ignition of the arc at the start of welding. 2 Il. about (L SLE 00 O) SP)

Description

This invention relates to the field of welding technology.

The purpose of the present invention is to reduce the level of radio interference, as well as to increase the efficiency of excitation and stabilization of the welding arc.

Fig. 1 shows the circuit diagram of the device; in fig. 2 - the form of current pulses through the arc gap.

The device contains an input transformer 15 to the secondary winding of which through diodes 2-5 are connected capacitors 6-9 of the thyristor switch 10, connected by an anode through transformer 11 and resistors 12-14 to capacitors 6-9, and by a cathode to a welding power source 15. The high-voltage pulse generation unit includes a transformer 11 and an oscillating circuit consisting of a capacitor 16, a surge generator 17 and the primary winding of a high-frequency transformer 13, the secondary winding of which is connected to the welding circuit 19 at the end and the other end to the welding source 15 and protective capacitor 20. The device also contains a thyristor switch 10 control unit consisting of a transformer 21 connected to a power source through resistors 22 and 23 and to a control

the thyristor electrode 10 through the diode 24.

The device works as follows

In one half-period of the mains voltage, the capacitors 6-9 are charged through diodes 2-5 to the amplitude value of the secondary voltage of transformer 1. In the next half-period, through transformer 21 and diode 24, a 1 control electrode of the thyristor switch 10 is supplied with voltage} sufficient for open it up The capacitors are discharged through resistors 12-14 and transformer 11. The capacitors are discharged with different time constants, forming a low voltage pulse. At the same time, a high-voltage pulse is applied to the arc gap, since condensate 6 is discharged through the trans: 1mator 11 in the secondary winding of which the oscillating circuit (capacitor 16 - discharge 17 - primary winding

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five

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transformer 18) generates and transmits with the help of transformer 18- to the arc gap a high-voltage bongge. Both pulses are formed when the thyristor switch 10 is opened, and the beginning of their action on the arc gap coincides.

The parameters of the electric circuit of the device are selected in such a way that the duration of the high-voltage pulse is several microseconds, which is ten times shorter than the duration of the low-voltage pulse.

The high-frequency pulse generator is turned off after energizing the arc either by shunting the transformer 11 or by breaking the charge circuit of the capacitor 6 with an arc relay (not shown).

In existing contexts, the form of a stabilizing pulse corresponds to the shape of a pulse from {Discharge capacitor to active resistance (Fig. 2, dashed lines). For this reason, in order to obtain the steep front of the pulse necessary for reliable stabilization of the arc, and with it pulse duration, overestimated the amplitude of the pulse current. It is 300–500 A in some devices, while S as the minimum value of a steady arc discharge current is 5 A. With such a value of the pulse current, the arc gap resistance is Ω, As shown by electrical calculations, a further decrease in arc gap resistance does not lead to a decrease in the time of zazkig and the arc from the main (welding) power source. The peak current of 300-500 A from the point of view of improving arc ignition reliability is useless, and from the point of view of radio interference and the danger of welding equipment failures (especially with programmed control or using robots) is very harmful. The proposed device makes it possible to obtain a Sh-Shul shape without an unnecessary current peak.

The pulse shape (FIG. 2, line 25) is obtained due to the fact that the individual capacitors and resistors through which they are connected to the switch have different parameters. They are with different constant times.

they are pressed onto the arc gap (Fig. 2, solid lines 26, 27 and 28). In sum, a current of 1/5 A flows through the arc gap - a predetermined time interval.

I

Diodes connected to each of

separate: capacitors, allow for one half period to charge the capacitor to the amplitude value of the input transformer voltage and ensure the independence of the charging voltage of individual capacitors from the discharge circuits of the adjacent capacitors, which simplifies obtaining the specified pulse shape of the device.

Compared with the known device, the generation of pulses during reverse polarity half-periods results in an increase in the excitation efficiency and stabilization of the welding arc.

 The unit for generating high-voltage and the advantages of the proposed device is 25 pulses connected to a thyristor

compared to the existing both switch and through it to the first

They are also sintered by reducing the radio output terminal of the welding power source at the junction of the protective capacitor and the generating unit.

interference generated by its operation, which makes it possible to use the device in conjunction with programming devices, robots in automatic lines controlled by computers, which ultimately provides an increase in the labor productivity of welders.

Claims (1)

Invention Formula Apparatus for initiating and stabilizing the welding arc, containing an input transformer, a thyristor switch, a resistor, a diode, a capacitor, a high voltage pulse generation unit connected to the welding circuit, and a protective capacitor connected in parallel to the welding power source, characterized in that, in order to reduce radio interference, diodes, n capacitors and n-1 resistors, with anodes of all the diodes connected to one of the ends of the secondary winding of the input transformer, each of which in turn connected by cathode to the plates of each capacitor, with their points of connection through separate resistors, and one point of connection through output terminal of the welding power source at the junction of the protective capacitor and the generating unit 30 high-voltage pulses, and the other capacitor plates are connected to a common point and connected to the other end of the secondary winding of the input transformer and to the second output,  35 welding power supply terminal,. zeff yy and Fig 7 / 0Lf.2 Editor I. Gorna Compiled by Tehred A. Kravchuk Order 6319 Circulation 922 Subscription VPIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk neb., d. A / 5 Production and printing company, Uzhgorod, yxi. Project, 4 Proofreader L. Obruchar