SU584999A2 - Device for stabilizing ac welding arc - Google Patents

Description

(54) DEVICE FOR STABILIZATION OF AC WELDING ARC

Anfly connected to the primary winding of a semi-pulse transformer, and the cathode to the secondary winding of the supply transformer connected according to the output power supply winding, a capacitor connected by one plate to the anode of the diode, and the other to the emitter circuit of the transistor switch, a diode connected in series with the capacitor differentiating circuit, and a resistor connected in parallel with this capacitor.

The drawing shows a schematic diagram of the proposed device.

The circuit contains a power transformer 1, an output node 2 with a switching element 3 and a capacitor 4, which serves to store the energy of the stabilizing pulse through the diode 5, and the control node 6.

The control unit consists of a differentiating circuit with a voltage divider 7, a capacitor 8, a diode 9 and a resistor 10, a negative differential circuit 11 with diodes 12 and 13 transis 1, a wrench 14, a capacitor 15, a diode 1 and G78 1 pulse transformer 17, the secondary winding which is connected through the diode 18 to the control transition of the switching element 3.

The device works as follows.

In the half-periods of the supply voltage corresponding to the direct polarities of the welding current ("- on the electrode," + on the product), the capacitors 4 and 15 are charged from the secondary windings of the supply transformer 1 through diodes 5 and 16.

When the polarity of the welding current changes from direct to reverse, a current flows through the differentiating chain (elements 9-7) that is proportional to the rate of voltage build-up in the arc gap. This current unlocks the transistor switch 14, and the primary winding of the semi-pulse transformer 17 receives the voltage of the capacitor 15, resulting in a current pulse in the secondary winding of the transformer 17, which unlocks the switching element 3. Thus, the discharge circuit of the capacitor 4, creating a stabilizing pulse .

Since the capacitor 15 is charged in the previous half period, the voltage across it does not depend on the moment of unlocking the transistor switch. As a result, the control signals of the switching element remain the same in magnitude at different shear angles between the idling voltage and the welding current, which increases the reliability of the stabilizer and the quality of the weld.

To protect against false alarms of the control unit under the action of disturbances on the arc, the gap in the half-periods of the direct field p-dst and the welding current in series with the capacitor of the differentiating chain, diode 9 is turned on. The capacitor is discharged through a resistor 10.

Diode 16 besides rectifying charge current

performs the function of an element that prevents the summation of the voltage on the capacitor with the voltage of the secondary winding of the supply transformer in the half-periods of reverse polarity of the welding current.

The described construction of the device makes it possible to increase its reliability in operation and, consequently, the quality of welded joints.

Claims (1)

1. USSR author's certificate number 496126 Cl. At 23 K 9/10, 1974. / vw ten „R--} ,, ir 9 1. I n  I „.„ I L one/.., i Psh -0 J6 L