SU361848A1 - ALL UNION? ^ - Google Patents

Description

one

The present invention relates to the field of welding and can be used for welding metal parts in the production of non-conductive resistors, vacuum tubes and other components and parts for the electronics industry.

Known devices for stabilizing heating for a point contact machine during mains voltage fluctuations, containing a welding transformer with a power switching thyristor and a control unit, a welding pulse duration setting unit including a reference voltage source, a dynistor, a potentiometer and a capacitor connected to a variable voltage source phase shifted relative to the feed at 90 ° C, are relatively complex and unreliable.

The proposed device lacks this disadvantage due to the fact that the source of alternating voltage is connected to the capacitor through a diode, the anode of which is connected to the anode of the dynistor.

The drawing shows a block diagram of the device.

The device consists of a welding transformer with a power switching thyristor and a control unit /, the node 2 setting the pulse duration of the welding current collected from the source 3 of the reference voltage,

a capacitor 4, a dynistor 5 and a potentiometer 6, a source of alternating voltage 7, shifted relative to the mains by 90 °, a diode 8, a zener diode 9, resistances 10 and 11. The source of alternating voltage (the voltage is shifted relative to the mains by 90 °) is connected in parallel to the capacitor 4 through the diode 8. The anode of the latter is connected to the anode of the dynistor 5. The source of the reference voltage

made of series-connected Zener diode 9 and resistor 10 connected to the mains voltage. Potentiometer 6 is used to set a predetermined pulse duration of the welding current at the nominal value of the mains voltage. The potentiometer // selects the magnitude of the control action of the device.

The reference voltage is applied at a frequency of 50 Hz in phase with the anode voltage of the thyristor, providing a charge for the capacitor 4. The signal of the alternating voltage source in the form of a one-half-wave pulse shifted relative to the mains voltage by 90 ° discharges the capacitor 4. In the welding half-period a capacitor is algebraically summed two voltages: full-wave | a variable voltage source and a reference voltage for a node with a duration setting. When the mains voltage deviates, the resulting voltage on the capacitor in the welding half-period determines the instant of switching on the dynistor, and, consequently, the phase of the output pulse of the duration setting node. When the net voltage of the capacitor exceeds the turn-on voltage of the dynistor 5, a short discharge pulse occurs through the diistor to the control unit 1. The latter contains, for example, a thyristor, the output circuit of which includes the machine control contacts and a pulse transformer to unlock the power thyristor . When you press the control contacts of the welding mask, a voltage is applied to the anode of the thyristor of the control unit. The first pulse of positive polarity of the discharge of the capacitor 4 through the dynistor 5 unlocks the thyristor. At the same time, a voltage pulse is generated in the windings of the pulse transformer, which turns on the power thyristor. As a result, a single pulse of welding current passes through the welding transformer.

To bring the circuit back to its original state, it is necessary to open the machine control contacts.

When the mains voltage changes, the amplitude of the half-wave pulse of the alternating voltage source changes. As a result, the charge rate of the capacitor changes as well as the moment when the dipistor is switched on. The unlocking angle of the power thyristor changes accordingly. In this case, the welding current acquires its original value. For example, as the mains voltage decreases, the amplitude of the welding current and the amplitude of the half-wave pulse decrease, and the charge rate of the capacitor increases. The unlocking angle of the thyristor is changed so that the pulse duration of the welding current increases. Thus, when the mains voltage deviates, the phase of the output pulses of the duration setting node changes, and the welding current takes on its original value. With a stepwise decrease or increase in the network voltage, a stabilization circuit performance equal to / 2 period of the network is achieved.

Subject invention

Heating stabilization device for a point contact machine with fluctuations

mains voltage, containing a welding transformer with a power switching thyristor and a control unit, a welding pulse duration setting unit, including a reference voltage source, a dynistor, a potentiometer and a capacitor connected to an alternating voltage source that is out of phase with the power supply by 90 °, characterized in that, in order to increase the reliability of its operation, a source of alternating voltage is connected to a capacitor through a diode, the anode of which is connected to the anode of the dynistor.