The power source for arc welding

 

(57) Abstract:

The invention relates to arc welding, in particular for electric welding machines AC lightweight design with low input current. The purpose of the invention is the improvement of conditions for igniting the arc, increasing the length of the arc gap and a wider range of regulation of the welding current. The power source for arc welding, containing a transformer with a primary winding connected through a counter-parallel connected thyristors to leads for connection to single-phase AC circuits series-connected capacitor and inductor, output circuits in parallel, each of which consists of a secondary winding of the transformer serially connected to the inductor, than parallel to one of the windings of the transformer included resistor. The total weight of the welding apparatus assembled according to this scheme, 15 kg at a current of 130A. 1 Il.

The invention relates to arc welding, in particular for electric welding machines AC lightweight design with low input current.

Adopted as a prototype power source for arc welding, containing the transformer with Pervy the heat AC, and a secondary winding, which is the output device, the transformer is provided with an additional winding located on the common to all windings of the magnetic circuit and is connected through a capacitor in parallel with the winding of the transformer [1].

A disadvantage of devices of the prototype is the weakening of control pulse leakage inductance of the transformer, which reduces the combustion stability of the welding arc. With series connection of a thyristor unit of the primary winding to the secondary winding of the transformer with a capacitor circuit loses control in modes that are close idle.

The purpose of the invention is the improvement of conditions for igniting the arc, increasing the length of the arc gap and a wider range of regulation of the welding current.

The aim is achieved in that the output circuits of the apparatus parallel, each of which consists of a secondary winding of the transformer serially connected with the winding connection of the inductor and parallel to one of the windings of the transformer included resistor. It improves the conditions of firing and increases the length of the arc gap. A resistor is parallel to one of the windings increases the momentum of the firing arc and the ez resistor has an inductive character, increasing the length of the arc gap.

The drawing shows a circuit diagram of a power source for arc welding.

The power supply consists of a transformer 1 having a primary winding 6 is connected through a counter-parallel connected thyristors 2 and 3 to the AC power supply 14. In parallel thyristors connected in series connected capacitor 5 and the coil 10. The inductor has two secondary windings 8 and 7, each of which is connected in series with one of the windings of the coils 11 or 12. Parallel to the secondary winding of the transformer 7 includes a resistor 9. Welding arc 13 are connected in series to the beginning of the transformer windings 7, 8 and the ends of the windings of the inductor. The control circuit thyristors 2, 3 are connected to the phase shifting unit 4.

The power supply operates as follows.

After switching on the system the phase shifting unit 4 submit short control pulses with a duration not longer than the period of the natural frequency of the oscillating circuit consisting of the inductor 10 and capacitor 5, with turn-on delay thyristors from the beginning of the rise of the half-waves of the supply sinupulse control thyristors capacitor 5 is discharged by oscillating the law through the inductance 10, recharged, and the current through the inductance, and hence, through the thyristors changes in direction, causing the thyristors are turned off. In the idling operation of the apparatus of impulses determined by the period of the natural frequency of the oscillating circuit consisting of a capacitor 5 and the inductance 10.

In the case of the arc energy of the capacitor is consumed through the inductance 10 and the windings 11, 12 to the welding arc 13, the capacitor is recharged and thyristors continue to burn until a time determined by the end of the half wave of the mains voltage and welding current.

Compared with the prototype in the proposed scheme, the circuit of the welding current splits into two branches, in varying degrees, affect the welding quality.

The first branch consists of the secondary winding of the transformer 8 and the winding connection 12 and is inductive in nature due to the inductances of the scattering of these windings and affect the smoothing of the ripple current welding, due to heterogeneity and contamination of the welded surface.

The second branch 7, 11 includes a resistor 9, which amplifies the pulse discharge current of the capacitor 5 on the arc 13 through 11, 10 and 7, because without rehobeth energy magnetizing current of the transformer and provides reliable switching thyristors, especially at low welding currents.

Thus, the proposed scheme improves the conditions for ignition of the arc increases the length of the arc gap and extends the control range of the welding current while maintaining the positive qualities of the prototype - reduce mass and size parameters of the transformer.

Practical results confirm these findings. So, when the same values of capacitance and inductance as in the prototype, and the apparatus assembled according to the proposed scheme, there is no need for pre-sorting of electrodes of alternating current and the opportunity welding electrodes constant current when the weight is 14 kg and a working current of 130 A.

The power source for arc welding, containing a transformer with a primary and two secondary windings and the primary winding of the transformer is connected through a counter-parallel connected controlled thyristors to conclusions to connect the power source to single-phase AC, condenser, one of the conclusions one of the secondary windings of the transformer is one of the outputs of the power source, characterized in that it is provided with a resistor and an inductor with two windings due to the connection of the inductor and United are the second output power source, and the second leads of windings connection connected each with its secondary winding, the latter findings are United and are the output of the power source, parallel to one of the secondary windings of the transformer is connected to the resistor.

 

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FIELD: methods for controlling ignition of welding electric arc at manual welding by means of coated electrode after breaking of short circuit between electrode and part.

SUBSTANCE: method comprises steps of touching welded part with electrode in place of welded seam beginning; exciting electric arc at time moment of electrode and part disconnection; detecting time moments of electrode and part touching and disconnection respectively by measuring changes of electric current and voltage in between electrodes. Electric arc is excited by three stages. At first in time moment of electrode and part touching short initial mode of hot starting sufficient for heating electrode is realized. After first time period short circuiting limitation mode is created when electric current value is sufficient for sustaining electrode in heated state without increasing contact area and close sticking. It provides controlled electrode sticking. At time moment of electrode tearing off secondary mode of hot starting with increased electric current is realized and electric arc is ignited between electrodes. Short initial hot starting mode is realized at electric current consisting 1.5 - 2 of preset welding current; duration of said initial hot starting mode is in range 0.5 - 1.0 s. Electric current value in short circuiting mode is selected in range 0.1 - 0.3 of preset welding current.

EFFECT: enhanced reliability of electric arc ignition process.

6 cl, 3 dwg

FIELD: welding processes and equipment, namely method for igniting DC arc by means of consumable electrode at automatic or semiautomatic welding.

SUBSTANCE: method comprises steps of setting extension of consumable electrode; turning on circuit for power supply of arc by electric current 1.5 - 6 A at inductance of welding circuit 5 - 15 mH and at discharge of capacitors with capacitance 1000 - 2000 mcF. Electric arc is ignited at touching by means of end of electrode with predetermined extension. After occurring on end of electrode extension liquid metal layer or drop, working arc power supply circuit is turned on and circuit for power supply of arc with electric current 1.5 - 6 A is turned off. Presence of solidified metal drop whose diameter exceeds that of electrode by 1.5 - 2.5 times on end of electrode corresponds to stable ignition of arc.

EFFECT: simplified process of arc ignition, stable ignition at presence on end of electrode solidified metal drop.

1 ex

FIELD: electrical engineering.

SUBSTANCE: reliability of repeated arc firing is estimated, in analysing coated electrodes, proceeding from actual conductivity magnitude defined in contact between flowed end face of interconnected electrode under analysis and metal plate. Obtained magnitudes of actual conductivity allow estimating reliability of repeated firing. Higher the conductivity, higher reliability of repeated firing.

EFFECT: higher accuracy of estimation.

1 dwg, 2 tbl

Method of welding // 2406597

FIELD: process engineering.

SUBSTANCE: invention relates to welding by consumable wire 13. Proposed method comprises removing slag from welding wire end, lighting welding arc 15 between welding wire 13 and processed part 16, and welding with feeding welding wire by wire feed mechanism towards processed part 16. Slag removal started, welding current is reduced to minimum. During slag removal, welding wire 13 is reciprocated, cyclically and repeatedly, towards processed part 16 with preset work stroke and with smaller stroke from part 16 unless control system detects short circuit between welding wire 13 and processed part 16 to strop welding.

EFFECT: reliable arc lighting.

10 cl, 3 dwg

FIELD: process engineering.

SUBSTANCE: method is intended for igniting arc in manual arc welding with combined soft and hot starting. Soft start is performed at short-circuiting the electrode to part. Hit start is performed in parting the electrode from the part and setting arc discharge. Soft start current is set subject to electrode diameter or preset welding current. Changing to hot start is performed in response to signal of voltage transducer that detects arc ignition at the end of soft start. Hot start current is set subject to electrode coating type and set welding current. Microprocessor-controlled power supplies are used including thyristor rectifier, inverter-based source or transistor station controller incorporated with multi-station rectifier system. Note here that in soft start auxiliary low-power HV infeed source.

EFFECT: higher reliability.

3 cl, 3 dwg, 3 ex

FIELD: electric arc welding processes and equipment, possibly manual electric arc welding by means of coated electrode that may be in different spatial positions.

SUBSTANCE: welding is realized by means of modulated electric current at separate regulation of pulse and pause duration of welding electric current. During pause additional pulses with amplitude equal to that of main pulses, frequency no less than 50 Hz, duration (0.5 - 2) ms are applied on small welding current 5 - 30 A. Heat power of welding current is automatically realized according to action of welding operator due to changing parameters of main pulses depending upon fluctuation of mean voltage of electric arc from predetermined value at relatively small change of arc gap (2 - 2.5)V.

EFFECT: lowered contrast degree of irradiation of electric arc during pulse and pause, enhanced quality of welded joint, possibility for controlling heat power of electric arc according to desire of welding operator, improved topography of welded seam.

5 cl, 5 dwg, 5 ex

FIELD: electric welding processes and equipment, namely regulated power source for manual electric arc welding, possibly in workshops, in domestic or industrial condition.

SUBSTANCE: inlet of bridge type diode rectifier is connected with one section of secondary winding of transformer. Two gangs of capacitors are connected in parallel with diodes of one arm of bridge type rectifier and with one outlet of said section. Smoothing choke with split windings is connected between arms of bridge type rectifier. Secondary winding of transformer includes additional booster section to which two thyristors are connected. Said thyristors are controlled by means of pulse-phase control system. The last includes double-threshold comparator whose inlet is connected with outlet of power source and whose outlet is connected with inlet for interlocking pulses of pulse-phase control system.

EFFECT: possibility for proving smooth regulation of welding electric current in desired range.

2 dwg

FIELD: welding processes and equipment, namely method for controlling manufacturing equipment providing pulse feed of welding wire to electric arc zone.

SUBSTANCE: method comprises steps of applying signal to adaptive system for controlling mechanism for pulse feed of welding wire. During automatic mode in said system control signal source is operated. Source of control signal is in the form of pickup for measuring welding wire force in guiding duct of welding hose and feed stroke pickup. Pulse is generated at time moment when welding wire achieves in guiding duct energy corresponding to optimal acceleration of welding wire motion. Pulse repetition frequency is set by adjustment of force pickup, by speed of feed mechanism and by stroke set by welding wire feed stroke pickup.

EFFECT: simplified control circuit, regulation of stroke of welding wire feed and therefore of size of drops of electrode metal transferred to welding bath.

1 dwg

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