RU2038935C1 - Consumable electrode arc welding - Google Patents

Abstract

FIELD: welding technique. SUBSTANCE: at the moment of beginning of shorting, current is decreased to 0 within time τ depending on energy consumed for forming drip which is acted on by additional electromagnetic energy. EFFECT: enhanced efficiency. 4 cl, 4 dwg

Description

 The invention relates to methods for arc welding with a consumable electrode with energy control during a short circuit time and can be used in all sectors of the economy.

A known method of arc welding with a consumable electrode with a short circuit arc gap, at which at the moment of formation of the neck of the jumper the current is reduced to a minimum value, and after its rupture is increased [1]
The disadvantage of this method is the difficulty of fixing the moment of formation of the neck of the jumper and, therefore, the timeliness of the decrease in current at the time of rupture of the jumper.

 The work of I. S. Pinchuk et al. Reducing spatter during short-circuit welding by limiting the explosion energy of a jumper (Welding, 1976, No. 11, pp. 52-54) shows the probability of normal commutation and the associated spatter coefficient.

A known method and device for the controlled transfer of electrode metal by short-term pulses of gas [2]
The disadvantage of this method is the need to create additional devices and limited application, since the method has a minimum coefficient of energy transfer of 0.7˙10 ^-4 s.

A known method of electric arc welding with a consumable electrode with short circuits of the arc gap, in which at the time of the beginning of the short circuit, the current is reduced to 2-30 A for a period of time in the range of 0.1-1 ms (0.1-1.0 ˙ 10 ^-3 s ) [3]
This method is taken as a prototype for this application. For given values of current and time of its flow, the method has limited application, since the drop transition time (short-circuit time) is determined by the mass of the drop and the diameter of the electrode, and these values are not acceptable for all electrode diameters and welding mode.

 The aim of the invention is to remedy these disadvantages by controlling the magnitude of the energy and its duration during a short circuit, depending on the mass of the droplet.

To achieve the goal in the method of arc welding with a consumable electrode with short circuits of the arc gap, at which the current is reduced at the moment of the short circuit, the energy affected by the formation of the droplet is determined before the short circuit of the arc gap, the current is reduced to zero by the time τ determined from the condition τ KE _k , where K is a coefficient that takes into account the parameters of the regime, E _{k is the} energy spent on the formation of the droplet, and additional energy is applied to the droplet to detach it. In this case, the dependence of the additional energy on the energy spent on the formation of the droplet at various parameters of the regime is additionally determined, and the value of the additional energy is selected in accordance with the obtained dependence. As additional energy use electrical, mechanical, electromagnetic energy. When used as additional electric energy, they act on the drop after the current reduction time has passed, and when using mechanical or electromagnetic energy, the drop is exposed to the drop during the short circuit of the arc gap.

 The proposed welding method, due to a combination of essential features, allows welding with short circuits with the transfer of each drop with a significant reduction in spatter with optimal control of energy parameters during the transition time of the drop into the bath.

 In FIG. 1 shows a diagram of the shape change of a drop when merged with a weld pool; figure 2 is a block diagram of the control of additional energy and welding current during the short circuit time; figure 3 and 4 of the cyclogram changes the welding current and additional energy from an external source during the short circuit time.

 The method of arc welding with a consumable electrode is as follows.

Before welding, determine the coefficient K, depending on the diameter d _{e of the} melting electrode and calculated by the empirically derived formula
K (6 ˙ 10 ^-4 -2.15 ˙ 10 ^-4 d _e ) x (0.018 + 0.0053 d _e ).

Then, it is estimated and experimentally corrected for various parameters of the mode (I _d arc current; U _d arc voltage; t _d arc burning time; d _e diameter of the consumable electrode (grade of welded and electrode material, composition of the protective gas) dependence of the additional energy of DE time τ _de its action on the energy E _k spent on droplet formation After preliminary determination of the indicated values, the welding process is carried out.

At the moment of excitation of the arc 1 between the part of the droplet 3 remaining on the electrode 2 and the bath 4 (see FIG. 1), block 5 fixes the energy E _k spent on the formation of droplet 6. The signals I _d , U _d , t _d from the arc 1 are sent to block 5, which determines the energy E _to
E _to I _d ˙ U _d ˙ t _d
Block 5 contains values of k for various diameters d _{e of the} melting electrode 2. At the moment the drop 6 touches the surface of the bath 4, block 5 gives signals: one about the beginning of a short circuit, the other about the value of time τ When a signal about the beginning of a short circuit arrives at control unit 7 unit 7 issues a command to arc power supply 8 to reduce current I _d to zero by time τ and a command to turn on an actuator 9 for supplying additional energy of DE to drop 6, in which predefined values of additional energy of DE are stored, in the belt τ _de its action, depending on the energy E _k , which goes to the formation of droplets 6 and into which the effective value E _k enters. The actuator 9, depending on the actual value of E _to sets the amount of additional energy DE acting on the drop 6 to accelerate the time of its transfer. After the expiration of time τ, block 7 issues a command to the arc power source 8 to increase the current (energy) to a level that excludes spatter of the electrode material when the jumper 10 breaks and arc 1 is excited. The process is repeated.

As additional energy of DE, external mechanical, electromagnetic sources (additional energy of DE _in ) and "internal" sources of electrical energy (additional energy of DE _I ) can be used.

In the case of external addition of energy _in DE latter affects the drop 6 during a short circuit (τ _KZ) (see. Figure 3) with electrical auxiliary energy _I DE latter acts on the drop at the end of 6 time τ absence of the welding current ( see figure 4). The introduction of DE _in has a positive effect on the process of droplet transfer from the point of view of reducing the short circuit time and eliminating the cause of spraying, which is why it is desirable. In this case, the energy of the welding current after τ is needed mainly for the subsequent arc excitation. The sum of energies should be sufficient for the transfer of drops below the critical volume.

 The method of arc welding with a consumable electrode allows you to fully automate the welding process, creating a mathematical model of the process and using computer technology.

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(5,8·10^-6)² в течение всего времени короткого замыкания.As an example of assessing the change in the energy parameters of the impact on a drop during the short circuit time of each drop, the quantitative dependences τ DE, τ _de for the case of welding steel 1X18H10T with Sv-04X19N11MZT wire with a diameter of 2.0 mm in argon medium are given below. In this case, τ 48˙10 ^-7 Е _к (s), where Е _к is the droplet formation energy, J. The critical volume of a droplet, less than which the droplet is transferred only under the action of additional energy, is determined by the value of the energy Е _к ^кр . In this example, E _to J 460 ^kr. When the energy E _{to E} of less ^Cr is necessary to introduce additional energy ED (J) is not smaller than the value defined by the formula
(De + 5.1 · 10 ^-6 ) ² + 86 · 10 ^-12

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(5.8 · 10 ^-6 ) ² during the entire short circuit time.

Если Е_к находится в пределах 165 < Е_к < <390 Дж, а дополнительная энергия 1,15˙10^-6-0,00265˙10^-6 Е_к < ДЭ_I ≅ 5,2˙ 10^-6--0,012E_к˙10^-6, то ДЭ рассчитывается по следующей формуле
τ_дэ= (2,2·10^-9- 0,003·10^-9E_к·

Если же ДЭ_I > 5,2˙ 10^-6-0,012 Е_к˙ 10^-6, то τ_дэ 1,9˙ 10^-6 Е_к 0,1Е_к ДЭ_I.To reduce the short circuit time, the amount of additional energy (DE _in ), introduced by an external source, can also be a large value. In the case of introducing additional energy by means of a welding current (DE _I ), the minimum duration of its action must be selected by the formulas depending on the volume of the droplet (the energy used to form the droplet) and the amount of additional energy. When E _to ≅ 165 J
τ _de =

If E is _to within 165 <E _h <<390 J, and additional energy 1,15˙10 ^{-6 -6} -0,00265˙10 E _{k <I} ≅ 5,2˙ DE 10 ^-6 --0,012E _to ˙10 ^-6 , then DE is calculated according to the following formula
τ _de = (2.2 · 10 ^-9 - 0.003 · 10 ^-9 E _to

If DE _I > 5.2˙ 10 ^-6 -0.012 Е _to ˙ 10 ^-6 , then τ _de 1.9˙ 10 ^-6 Е _to 0.1 Е _to DE _I.

Similar dependencies were also determined for the case E _k > 390 J.

The calculation of the values of τ DE, τ _de can be done for any diameter of the electrode, shielding gas, the composition of the wire and the main material. The table shows the values of τ, DE, DE _I , the time of its action, τ _DE for three different values of the energy spent on the formation of droplet E _k (droplet volume).

 Thus, the proposed method of arc welding with a consumable electrode with short circuits of the arc gap allows controlling the droplet transfer process taking into account the perturbations acting on it, eliminating (significantly reducing) spatter, and also provides an increase in the productivity of the process by reducing the short circuit time while maintaining the quality of the connection.

Claims (4)

1. METHOD OF ARC WELDING BY A FLOATING ELECTRODE with short circuits of the arc gap, at which the current is reduced at the time of the beginning of the short circuit, characterized in that before the short circuit of the arc gap, the energy spent on droplet formation is determined, the current is reduced to zero by the time τ, determined from conditions τ = kE _k , where k is a coefficient taking into account the parameters of the regime; E _{to the} energy spent on the formation of a drop, and the drop is affected by additional energy for its separation.  2. The method according to p. 1, characterized in that the separation of the droplet is carried out by additional electric energy, which is supplied after reducing the current to 0.  3. The method according to p. 1, characterized in that the drop is separated by additional mechanical energy, which is supplied during a short circuit.  4. The method according to p. 1, characterized in that the separation of the droplets is carried out by additional electromagnetic energy, which is supplied during a short circuit.

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