SU984755A1 - Apparatus for electric arc welding by modulated increased-frequency current - Google Patents

Description

The invention relates to welding production, in particular to devices for electric arc welding with modulated current of increased frequency and can be used mainly in manual arc welding with portable welding machines.

A device for electric arc welding with a modulated high-frequency current containing an inductive ballast resistance, a high-frequency transformer, the secondary winding of which is connected to an electrode-product gap, a switch connected between the supply network and the primary winding of the high-frequency transformer, and a welding current limiting unit power sensor and sensor gauge and.

A significant disadvantage of this device is the inability to use it in the field, as well as during individual use in installation and repair work.

This is due to the fact that in the known device there is no possibility of individual generation

high frequency currents and for its operation, either a multipoint network or a separate high frequency current generator is needed.

A device is known in which a full-wave rectifier, an auto-oscillator and a pulse shaper connected by

10 in series and connected between the mains supply and the control input of the switch.

The disadvantage of this device is the low quality of welding and

15 reliability of its work, due to the absence of the possibility of software control of the arc by modulating the average welding current frequency.

The purpose of the invention is to increase the quality of welding and reliability of the device.

The goal is achieved by the fact that, in an electric arc welding device, a modulated high-frequency current containing inductive

25 resistance, high-frequency transformer, the secondary winding of which through inductive Resistance is connected to the output terminals of the device, a switch connected between

The 30 input terminals of the power supply network of the extended frequency and the primary winding of the high-frequency transformer, full-wave rectifier, autogenerator and amplifying pulse driver connected in series and connected between the input terminals of the power supply network and the control input of the switch, as well as the control and limiting unit for welding current with a power consumption sensor and a thermal sensor; a controlled voltage divider, summing pulse former, adder, differentiating link and knots compensation of the transformer magnetization, while the power consumption sensor is made in the form of an additional winding of the high-frequency transformer wound in the path of the scattered fluxes of the full-wave rectifier connected to one of the pulse shaper inputs through a voltage divider, to the control input of the divider connected to the output of the adder to the second input of the summing pulse former, connected to the output of the differentiating link connected by its input to the output of the welding limiting unit eye, limiting the welding current node, together with a programming node modulation process welding current and a temperature sensor is also connected to the inputs of the adder, and bias compensation part transformer is connected to the second input of the oscillator. Figure 1 shows the diagram of the device; Fig. 2 shows diagrams for the operation of the device. The device contains a high-frequency transformer 1, the secondary winding of which through the ballast inductance resistance 2 is loaded on the arc gap — the output terminals of the device 3, and the semiconductor switch 4 connected by the outputs to the primary winding of the transformer, and the input to the power supply network of the industrial frequency — the input terminals of the device . The control input of the switch 4 is connected to the output of a series-connected amplifying driver 5 impulses and an oscillator b. A full-wave rectifier 7 connected by its output through a controlled divider 8 to one of the inputs of the summing driver 9 pulses connected, in turn, to one of the inputs of the autogenerator 6 is connected to the power supply network, input terminals. To the control input of the divider 8 through the adder 10 the outputs of the node 11 are connected. Programming the modulation process of the welding current, the nodes 12 of the welding current limitation with the power consumption sensor 13 and the thermal sensor 14. Between the second input of the summing generator 9 pulses and The welding current limiting unit 15 is connected to the differentiating element 15, and the biasing compensation unit 16 of the transformer 1 is connected to the second input of the autogenerator 5. The device operates as follows. When the device is connected to the mains, the control input of the switch 4 receives impulses from the output of the amplifier driver 5 pulses, excited by the oscillator 6, modulated in frequency and duty cycle. Frequency modulation is set by a full-wave rectifier 7, the output signal of which and, accordingly, the modulation depth is controlled by the controlled divider 8, and after adding to the constant component in the summing shaper 9, it is fed to the input of the frequency modulation of the auto-oscillator 6. Divider 8 is controlled by the adder 10 , summing the control signals of the welding current modulation programming unit 11, the welding current limiting 12 and the temperature sensor 14, the modulation programming unit contains an arc voltage comparator and mu This sets a two-level frequency modulation depth, with an average low frequency corresponding to a welding pulse, an average large frequency of a pause. The power consumption limiting unit 12, comprising a rectifier with an integrating element and a comparator, is powered by a winding 13 of a transformer 1 wound over the Transformer on the path of the scattering of its magnetic field. The limitation of power consumption during short arc sinking and magnetization of the transformer core is achieved by raising the depth of the half-period modulation and, accordingly, to the average frequency of the oscillator. At the same time, the increasing ballast inductive resistance limits the welding current, and the decreasing range of induction of the magnetization reversal of the core limits its saturation. Thermal sensor 14 on the basis of a thermistor causes an increase in the depth of the half-cycle frequency modulation and, accordingly, the average frequency of the oscillator when the device overheats. This reduces the heating rate of the apparatus, and the drop in arc power indicates to the welder the need to reduce the time of continuous work. The autogenerator is additionally modulated in frequency by means of overcurrent protection during switching on and short shifts x arcs.

The overcurrent drive is provided by a differentiating link 15 connected to the second output of node 12 and forming a falling signal that is added to the half-period modulation signal at the input of summing driver 9 and causes the maximum to nominal minimum frequency to change. This achieves a reduction in the induction range of the magnetization reversal of the saturable core of the transformer 1. for a transient time. The modulation of the duty cycle of the autogenerator b compensating the magnetization of the transformer 1 due to the asymmetry of the electric circuit and the welding arc 3 by equalizing the volt-second areas of the positive and negative half-waves of the output voltage, sets the bias compensation section 16, which contains an integrating filter with an interfering limiter. The input node 16 is connected parallel to the arc gap 3, and the output is connected to the input of the latitude modulation of the oscillator. B.

The operation of the device is explained by diagrams (FIG. 2), where 1 is the final amplitude-time diagram of the welding current and 2 is causing its -1a modulation diagram of the welding current frequency regulating the ballast inductance. When the device is idled, simultaneous operation of all frequency modulation control devices cause a decay of the minimum frequency of the oscillator from the maximum 3 to the set nominal 4 under the action of the signal from the differentiator 15, while minimum frequency and superimposed on the half-cycle modulation qi rectifier 7 with adjustable divisor 8 depth. The increments 5 (pause) and 6 (impulse) are set by the amplitude-time programming device by current modulation, the increment 7 is superimposed by the device 12 to limit the required power at switching on (0, .. t) and short circuit (t ... t2). increment 8 by thermal sensor 14 in case of overheating of the apparatus (t3 ... ..14).

The inequality of the voltsecond areas of the half-periods of the welding voltage due to the valve effect and the asymmetry r of the electronic circuit is allocated by the node 16 and controls the value of the autogenerator 6 to compensate it.

Thus, this device for arc welding with a modulated high-frequency current allowed, in comparison with the basic prototype o-object, to make it possible to control the depth of the half-period modulation of the welding current and thereby improve the quality of welding and the reliability of the device.

Claims (2)

1. Journal of stauto und Omnibus, 1965, 9, p. 8 (him). 2. USSR author's certificate No. 600675, cl. H 02 M 5/293, 07/04/74 (prototype). it. d ag.1