Electric arc welding method by means of consumable electrode with pulse modulation of current

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

 

The present invention relates to electric arc welding of metals and can be used for manual arc welding electrodes coated and argon-arc welding with non-consumable electrode in different spatial positions, as well as for automatic gas-shielded welding with non-consumable electrode.

There is a method of manual arc welding electrodes coated with pulse modulation mode settings for direct and alternating current at which the arc current is periodically increase (pulse) and reduce (pause) relative to the current for a given electrode in a continuous mode. To preserve the stability of arc burning in the pause or increase the open-circuit voltage of the power source (60 volts), or served on the arc gap of the high-voltage pulses with amplitude of 0.5 to 0.9 kV, duration of 20-40 μs) at the moment of transition of the current through zero. The frequency of major pulses of welding current is within 1-25 Hz (Dudko D.A., Sidoruk B.C., Zazerkalye S.A., Makhlin NM, Fedotenkov VG, Vikulov VG Technology manual arc welding with coated electrodes with modulation mode settings. //Automatic welding. - 1991. No. 12. P.59-60).

This method has the following disadvantages: since the current pulse and the current pause differ significantly, the light emission of the arc during the pulse and pause as well), the public differ and the pupil of the eye welder due to the low modulation frequency (1÷ 25 Hz) time to respond to changing light flux that tired of it and limits the use of such a process. In addition, due to the difference in the values of the current pulse and pause the welded seam is formed grade, which leads to the possibility of occurrence of undercuts. And when welding on the descent may leak under the electrode slag and metal bath during pauses. Therefore, the duration of the pause may not be large, which limits the adjustment process capability.

There is a method of manual arc welding modulated current at which the current pulse disable the lengthening of the arc, and the length of the pause is automatically set in inverse proportion to the duration of the preceding current pulse. The pulse frequency of the welding current according to the method is in the range from a fraction of a Hz to units of Hz (As the USSR. The way of manual arc welding modulated current / Afresco, Aguazul, Riyadh and other bull. No. 6, 15.02.82). This method has the following disadvantages: different intensity of light during the pulse of welding current and pause, which negatively affects the vision of the welder, the possibility of occurrence of undercuts due to krupnoigolchatogo seam due to the large difference of the currents of the pulse and pause, "primerzanie" electrode in the pause during the transition to a drop in the welding in the nnu during short circuit, since the current pause is small. The technique of this method is complicated and tedious, because the welder should with a frequency of several Hz to lengthen or shorten the length of the arc.

There is a method of electric arc welding modulated current electrodes with a coating of any type in which during pause when welding vertical seams on the descent impose additional pulses of variable duration, the time of their inclusion is determined depending on the fluidity of the bath, which is determined by the change in arc voltage specified, and the length of additional pulses is installed in the return depending on the time of cold metal to a critical situation. The frequency of additional pulses does not exceed 10-15 Hz (A.S. 1131618 the USSR. The method of electric arc welding modulated current / Rigidum, Afrmation, Nasarov, Aguazul. Bull. No. 48, 30.12.84. The prototype). The method has significant drawbacks, since the frequency of the additional pulses 10-15 Hz the pupils of the eyes of the welder will be able to respond to changes in the intensity of the light flux. Krupnoigolchatogo seam remains. And because the duration of the primary and secondary pulses and pauses is set by a program, the welder cannot control thermal power of the arc. That is, in the welding process will be practiced concept (machine technology), welder this is sluchin from the management of thermal power of the arc.

Object of the present invention is to provide a method of welding with automatic control of the heating capacity of the arc, and hence the rate of welding while improving the quality of a welded joint when welding in all positions and reducing the load on sight.

This object is achieved in that the method of electric arc welding with pulse modulation of the welding current is carried out by adjusting the duration of the pulses and pauses in the flow of welding current and overlay during pauses additional current pulses. The frequency of additional pulses choose the greater of 50 Hz and a duration of 0.5 to 2 MS, and the duration of the main pulses and pauses automatically regulate the functions of the deviations medium voltage arc gap from a given change in the arc length. Management of thermal power carry out the desire of the welder automatically. The parameters of the pulses change in function of the deviation of the medium-voltage arc gap from the set defined independently of the main pulses and pauses in different variants, excluding the effects of fluctuations in the tub and drops.

Depending on the medium voltage arc gap, i.e. lengthening and shortening of the arc at the request of the welder, the parameters of the main pulses and pauses ODA the process identifies functional deviations from medium voltage arc gap from the set during the main pulse and main breaks. The voltage is equal to the rated voltage for a specific electrode.

The duration of the main pulse is inversely proportional to the average voltage of the arc.

Further, the invention is illustrated by drawings, which depict:

- figure 1 shows the plot of current and voltage of the arc gap, explaining the proposed method;

- figure 2 presents plots of current and voltage when the modulation of the duration of the main pulse, which will be determined inversely related to the defined functional deviations from medium voltage arc gap from the one set on the interval of the pulse;

- figure 3 presents plots of current and voltage of the arc gap by modulation of the duration of main breaks;

- figure 4 presents a plot of the voltage and current of the arc gap with a simultaneous modulation of the duration of the main pulses and pauses.

- figure 5 is a plot of voltage and current when the modulation level deviations medium voltage arc gap from specified when the relay mode.

According to the proposed method, the following options control thermal power of the arc at the request of welder change in the arc length: modulates the duration of the main pause; modulates the duration of the main pulse; modulate the Xia at the same time the duration of the main pulses and pauses; is the relay mode - when the elongation of the arc to a voltage exceeding the specified voltage equal to the rated current of the electrode, current mode pause with the imposition of additional pulses, and when the shortening of the arc to the nominal electrode and below is a current mode pulse.

Depending on the voltage of the arc gap, i.e. lengthening of the arc at the request of welder duration of the main pulse is determined by the functional deviations from medium voltage arc gap from the set during the pulse. The duration of the main pulse is inversely proportional to the deviation of the voltage of the arc gap from the specified value.

The duration of the main pause determine functional deviations from medium voltage arc gap during the main pause from the set. The duration of the main pause is directly proportional to the deviation of the arc voltage from the specified value.

Feedback voltage only changes the duration of the main pulse, the duration of the main pause or change them at the same time.

Possible relay mode arc when the arc voltage is less than the specified continuous welding current a long time, and in the lengthening of the arc is the current pause with the imposition of the auxiliary pulses.

usnot of the proposed methods is as follows. The arc gap is fed by pulses of constant current, between which burns duty arc, which impose additional pulses of constant frequency and duration, which are set before starting the welding of technological considerations. The plot of the current of the arc gap at a constant durations of the main pulses and pauses are presented in figure 1. The frequency of additional pulses must be at least 50 Hz and their duration in the range of 0.5÷2 MS. With such parameters ensures a guaranteed drop transition on the main interval pause during a short circuit the drop of the arc gap. The value of the continuous current pause equal 5-30 A.

Figure 1-5 the following notation:

T con. - the duration of the repetition period of the main pulse;

t ion. - the duration of the main pulse;

t posn. - the duration of the main pause;

J ion. the amplitude of the main pulse;

J ISP. the amplitude of the auxiliary pulse;

T TWSP. - the duration of the repetition period of the auxiliary pulses;

t ISP. - the duration of the auxiliary pulse;

t PSP. - the duration of the auxiliary pause;

Ua - voltage arc gap;

U specified voltage arc gap, equal to the nominal voltage for a particular electrode;

J - continuous current spouse.

When modulating the duration of main breaks (figure 3) and the duration of the main pulse (figure 2) they will depend on the error signal: ±ΔU=Ua-U; where Ua - voltage arc gap, and U specified voltage, which is nominal for each group of electrodes, which can be combined according to the following General parameters - brand, coating thickness, diameter. At a given voltage and the constant voltage idling current source is set in the main pulse, the optimum for a given electrode, which is constant and not dependent on other parameters.

During welding, the welder can adjust the length of the arc, this will ΔU different in magnitude and sign of the relative U, modulating one of the main parameters pulse duration main breaks, or the duration of the main pulse.

Examples:

1. Weld root weld connection rotary joint of pipe with a V-shaped cutting edges. Welding is carried out with electrodes coated UONI-13/45 3 mm in diameter modulated current injected into the welding circuit is pulse-controlled resistance (IRS).

The current main and auxiliary pulses set the rated current of the electrode is equal to 140 A.

When welding with software control the duration of the main pulse setting is up equal to 0.25 s, and the length of the main pause to 0.3 C. the frequency of the auxiliary pulse is set to 55 Hz, and the duration of the auxiliary pulse is equal to 1.3 MS. Continuous current in the main break, which impose auxiliary pulses is set to 15 A.

After initiation of the arc welder uniformly maintains the electrode along the seam without manipulation. At the time of the main pulse of prescribed duration is melted and transferred to the weld pool from one to several drops with a short circuit during the transition. If the drop transition occurs during main breaks, it does not reduce technological stability, because the energy of the auxiliary pulse is enough to ensure rapid transition to the weld pool. Therefore, additional measures to accelerate the destruction of the bridges between the drop and the electrode during a short circuit on the main interval of the pause is not required.

In connection with high frequency auxiliary pulses with the same amplitude as the main pulse, the contrast of the radiation of the arc between the main pulses and pauses significantly reduced, which significantly reduces the load on the vision, and the welding seam is formed, fine-flaked.

This process may be used when welding thick sections, when it doesn't nakoplenie the heat and increase the temperature of the product before arc, and the butt joint and the dulling of the edges is quite stable. Otherwise, apply one of the following pulse modulation.

2. In this embodiment, the duration of the main pulse of welding current automatically set inversely proportional to the deviation of the arc voltage from the one set on the interval of the main pulse. Moreover, when the elongation of the arc, the minimum pulse duration is automatically limit on the level of 0.1 s, while the shortening of the arc at the level of 0.6 C. the Duration of the main pause set constant and equal to 0.35 C. All other parameters set as in program management (see example 1).

The voltage is set to the 24th Century With equal arc voltage specified duration of the main pulse of 0.3 C. the Increase in arc voltage of two volts automatically reduces the duration of the main pulse of 0.1 s and a decrease in arc voltage relative to a set of two volts automatically increases the duration of the main pulse to 0.6 C. Thus, at the interval of 4 volts, the duration of the main pulse automatically change within 0.1÷0,6 C. Welder depending on the situation in the arc gap and their abilities to adapt mode settings, providing qualitative formation of W is a and it is possible for him welding performance.

3. In this embodiment, the duration of the main pause set automatically in direct proportion to the deviation of the arc voltage on the main interval pause within 0.1÷2.0 sec, and the duration of the main pulse is constant and equal to 0.3 C. All other settings are set the same as in the previous case (see example 1). In case of equality of arc voltage to a specified voltage, the duration of the main pause equal to 0.4 C.

The increase in arc voltage of two volts automatically increases the duration of main breaks to 2.0, and the decrease in arc voltage by 2 volts automatically reduces the duration of the major pauses to 0.1 C.

Welder smooth change in voltage arc gap adapts the parameters of the welding mode depending on the situation in the arc gap and its capabilities.

4. In this embodiment combines the two previous options modulation parameters of the pulses (see example 2, 3).

Changing the arc voltage within ΔU=±2 B automatically at the same time change the duration of the main pulse in the range of 0.1÷0.6 and main breaks within 0.1÷2,5 C. And reducing a voltage of the arc relative to a set at 2 volts automatically set the duration of the main pulse is equal to 0.6, and the length of main breaks equal to 0.1 C.

When the arc voltage, equal, automatically set the duration of the main pulse of 0.3 s, and the length of the main pause equal to 0.4 C.

This variant of the modulation parameters of the pulses of welding current offers broad opportunities for adaptation mode settings in accordance with the situation in the arc zone and capabilities of the welder.

5. In this embodiment, in function of the deviation of the average arc voltage from the set automatically implement the relay mode. The arc can burn in a continuous mode when the current value of the main pulse, or when the current value of the main pause with the imposition of the auxiliary pulses. The duration of flow of the primary current and the primary pause automatically set as a function of deviations of the average arc voltage from the set. When the arc voltage is less than 1.0 In the specified automatically include the main current. If you increase the arc voltage by 1.0 In the above-specified automatically reduce the current to a current pause with the imposition of the auxiliary pulses. This mode provides the welding of small thickness. It is convenient to study welding modulated current.

Presents methods of welding with pulse modulation provide the following advantages compared with the known:

decreases the contrast of the radiation pulse and the pause of the arc;

- improved top the graphy seam;

- improved degassing molten weld pool;

- there is possibility to control thermal power of the arc at the request of welder minor change in the arc length;

- reduced the learning process welder.

1. The method of electric arc welding with pulse modulation of welding current regulation duration of pulses and pauses of the welding current and the overlay during pauses additional current pulses, characterized in that the frequency of additional pulses choose the greater of 50 Hz and a duration of 0.5 to 2 MS, and the duration of the main pulses and pauses automatically regulate the functions of the deviations medium voltage arc gap from a given change in the arc length.

2. The method according to claim 1, characterized in that the duration of the main pulse of welding current automatically set inversely proportional to the deviation of the voltage of the arc gap from the one set on the interval of the main pulse.

3. The method according to claim 1, characterized in that the length of the major pauses automatically install directly proportional to the deviation of the voltage of the arc gap from the one set on the main interval pause.

4. The method according to claim 1, characterized in that at the same time automatically sets the duration of the main pulse in the back of Ministers the national dependence on the deviation of the medium-voltage arc gap from the one set on the interval of the main pulse, and the length of the major pauses in direct proportion to the deviation of the medium-voltage arc gap from the one set on the main interval pause.

5. The method according to claim 1, characterized in that the duration of pulses and pauses determine the change in the arc length.



 

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The invention relates to arc welding, in particular to devices for pulsed power welding arc, and can find application in various engineering industries for welding

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.

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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.

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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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SUBSTANCE: invention relates to two-stage electric arc welding sets and methods of their operation. Proposed set includes quick-acting impulse supply source 10 with controller 130 for implementing first and second welding processes in space between part to be welded W and welding wire E moved in direction towards part W. During first stage first current signal waveform is used, and during second stage, second current signal waveform. Circuit is provided to change over first and second welding processes. Change-over circuit includes counter 212 to count signals during first and second processes, and circuit 190 to change over from one welding process to other welding process at moment when counted signals in carried out welding process reach preset value for this process. Invention provides quality gas-shielded welding by consumable electrode with changing over of welding process with transfer of metal owing to surface tension, or process of welding at constant stress with jet transfer to other process of welding.

EFFECT: enlarged operating capabilities.

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EFFECT: enhanced reliability of welding process.

34 cl, 6 dwg

FIELD: welding jobs.

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EFFECT: welding pipelines together.

43 cl, 18 dwg, 3 tbl

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EFFECT: control of fused metal bath to produce high-quality welded seam.

6 cl, 6 dwg

FIELD: welding.

SUBSTANCE: invention relates to a method and device for consumable-electrode arc welding and can be used in manual or machine welding of joints of main and industrial pipelines, as well as other metal structures in different industries. When welding, transfer of electrode metal is controlled during the short circuit period. Before the short circuit, welding current is bridged and reduced to zero. Then during the short circuit period, welding current is varied proportionally to electrical conductivity of the liquid metal jumper. At the end of the short circuit, welding current is once again reduced to zero. After the short circuit, bridging is stopped and arcing is induced at the peak level of welding current, which during arcing, is gradually reduced to a base level. The device has a direct current power supply, throttle, current sensor, control unit, electrode, stabilitron, delay line and N diodes, connected in series and accordingly. The throttle has an impregnable magnetic core and a split winding.

EFFECT: prevention of metal sputtering during the short circuit period.

3 cl, 3 dwg

FIELD: electricity.

SUBSTANCE: tandem welding system comprises spaced apart electrodes for movement with same speed and jointly making weld joints. A data storage device stores measured data for each electrode when making a weld joint. The device carries out a process, which includes selection of measured data for each electrode, corresponding to the electrode passing through a control position and comparison of selected measured data of several spaced out electrodes for calculation of the weld joint parametre of the tandem welding system in the control position.

EFFECT: increased operational reliability.

38 cl, 8 dwg

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SUBSTANCE: arc is fed by pulsed welding current with parametres that allow arcing in dynamic mode. Arc, in above conditions, features high physical stability given a concentrated heat feed into welded product. Proposed method provided for control over heat feed by smoothly varying pulse repetition frequency and preset current pulse amplitude through variation of power supply voltage and stepwise variation of pulse duration in inverse proportion to departure of mean voltage at arc from preset voltage.

EFFECT: through penetration, formation of keyhole-type pilot hole and root pass in various positions of weld pool.

3 dwg, 1 ex

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