SU403519A1 - • NLATtii ^ -thayi & ESSh “-E * 2 **"? E "* ftS6AM. Cl. at 23k 11 / 24UDK 621.791.763.1 (088.8) - Google Patents

Description

one

The invention relates to welding and can be used in machines for contact micro-welding with split-electrode electronic microcircuits, as well as for two-way contact welding of parts of small thickness and cross sections.

A device for contact micro-welding with an increased frequency current is known, comprising a welding transformer, a working capacitor, a series inverter, a feedback system for a load voltage, and a controlled excitation system.

However, such a device is characterized by a low KPD, a narrow control range and the impossibility of simultaneously adjusting the amplitude, duration and duty cycle of the load current pulses.

The proposed device is characterized in that, in parallel with the primary winding of the welding transformer, during the fall of the load current pulse, a shunt capacitance is connected by means of two anti-parallel-connected thyristors. The switching times of these thyristors, set by the feedback system for the load voltage controlled by the excitation system through the constant delay lines relative to the switching on of the corresponding inverter thyristor pairs, determine the time of the last state turned on, the magnitude of the voltages

working and shunt capacitances, therefore, the amplitude and duration of the welding current pulses. This improves the quality of welding.

FIG. 1 shows the electrical circuit of the device; in fig. 2 — auto-tuning curves for the amplitude and duration of welding current pulses, where a is the control pulses on the thyristors; b - welding current

and the voltage on the working capacitor C in - the voltage on the shunt capacitor C.

The device is designed as a standalone

a bridge serial inverter consisting of Ti-Ti thyristors, a working capacitor Ci, a welding transformer (HS) as the inverter load. Parallel to the primary winding of the welding transformer, a series of two oppositely connected thyristors Ge and Tb H of capacitor Cz is connected. A feedback system (SOS) is connected to the welding electrodes, the output of which is connected to the excitation control system (YCB). The outputs yes are connected from one arm to the control electrodes of the thyristors TI and T3, then through the constant delay line (LPS) to Ge, from the other arm -

to TZ and through LPZ to T. The inverter is connected to a power source with an accumulative (ballast) capacitor. When TI and TS thyristors are turned on, a saar transformer passes the current determined by the parameters of the TC circuit - Ci, which is chosen so that the process is oscillatory in nature. Moreover, the frequency of natural oscillations of the TC-Ci circuit is higher than the frequency of the following starting, their excitation pulses .10 The working capacitance Ci is recharged through a transformer to a voltage greater than Ut). With a constant delay (pz) with respect to the turning on of the thyristors 72/4, a pulse is applied to the control electrode of the thyristor and TS- The thyristor Tb is switched on and under condition c, (+) (-). the thyristors are locked, the charge of the working capacitor C is stopped, and the capacitor C is recharged along the circuit of the oscillating circuit Cz-20 (polarity (-) (+)). When the current drops to zero, the thyristor closes. Thus, when the thyristor TS is turned on, the energy stored in the transformer and 25 bypass capacitor Cz is transferred to the load. The moment of switching on T with respect to turning on TiTa sets the pulse duration of the welding current, the voltage value at the working capacitor Ci and, consequently, the amplitude of the current of the next pulse. With a decrease (increase) in the amplitude of the load voltage, the frequency of the control is increased (decreases), and their impulses USV35 to the thyristors T Тз-TzTi ,. A change in frequency leads to a shift in the thyristor switching points Gz, TE (T relative to the switching on moment, a) and to a change in the on time of the thyristor 40 4 TiT3-TzT (, 4), which determines the amplitude and duration of the load current pulses. With increasing frequency, the amplitude and duration increase, and with decreasing decrease. Such a system allows the amplitude and duration of the load current pulses to be controlled as the frequency of the pulses changes, so that the effective value of the voltage between the welding electrodes remains constant or falling. The inclusion of a sequence of two oppositely connected thyristors and a shunt, her capacity parallel to the primary winding of the welding transformer allows you to adjust the duration of the series inverter. There is no need to drop the voltage from the working capacity to the resistance, which significantly increases the efficiency. system, allows to reduce the value of Sb. The invention of the device for contact micro-welding with a high-frequency current, containing its St.-arched transformer, a working capacitor, a series inverter, a feedback system for load voltage and a controlled excitation system, characterized in that, in order to improve the quality of welding, parallel to the primary winding of the welding transformer, a series circuit is connected, including a capacitor and a two-way key, made in the form of anti-parallel thyristors, control electrodes to toryh through constant delay line are connected to outputs sootvetstvuyushaya controllable drive system associated with the system output .we feedback. .

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