JPS62203673A - Feeding control method for consumable electrode in direct current welding equipment - Google Patents

Abstract

PURPOSE:To form a flat bead by minimizing a spatter generation quantity by stopping the feed of a consumable electrode by detecting the variation in the welding voltage or welding current at the moment when a short circuit is caused and by performing the feed of the consumable electrode at the arc regeneration time. CONSTITUTION:A feeding motor 4 is subjected to ON-OFF work with the welding voltage value generated by an arc 2 or the welding current value generated by a shunt 13 as the input signal, in case of performing a short circuit transfer arc welding a consumable electrode 1 and base metal 3 by a direct current power source 6. With the start of welding said input signal by a detection circuit 7 is compared with the signal of a reference circuit 9 in a comparison circuit 8 via a differential circuit 10 and outputted to the switching circuit 12 with brake for feeding motor via an amplifier circuit 11. The feed of the electrode 1 is thus stopped at the moment when a short circuit is caused and the electrode 1 feeding is performed at the arc re-generation time. The flat based on the thus be formed by minimizing the spatter generation quantity.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is directed to a DC welding device for a consumable electrode type DC arc welding method in which short circuits and arc generation are repeated between an extinguishing IL electrode and a welding paste material. The present invention relates to an electrode feeding control method.

(Prior art) The conventional DC welding power source with constant voltage characteristics used in the consumable electrode type DC arc welding method, which repeats short circuits and arc generation, a constant speed discharge JIl, and an electrode feeding method are shown in Figure 2. The transition process is shown as follows, where l is a consumable electrode, 14 is a droplet formed at the tip of the consumable electrode, 3 is a molten Ia base material, and 2 is an arc. Figure 2 (a) shows an arc generated from the tip of the consumable electrode l, and Figure 2 (b) shows an arc 2 generated from the tip of the consumable electrode l.
(C) shows a short-circuit state where the droplet 14 contacts the welding base metal 3, and (d) shows the droplet 14 moving toward the welding base metal 3 and growing. (e) shows a state in which the short circuit is broken and an arc 2 is generated, and (f) shows a state in which the constricted droplet 14 is broken and spatter 15 is generated. The processes from ) to () are repeated. − Spatter occurs at the moment when the droplet disappears, becomes large at the tip of the electrode, and short-circuits with the welding base metal, or when the droplet is crushed by the electromagnetic pinch force at the tip of the consumable electrode. It has been reported that the particles become spatter and jump.

In particular, at the moment when the droplets from de-polarization short-circuit with the molten Jli/17 material, the welding voltage becomes extremely low as shown in FIG. 3, and conversely, the welding current reaches its maximum like a surge waveform. The energy at this time blows away the droplets at the tip of the consumable electrode, generating spatter. In this case, the consumable electrode is fed continuously at a preset constant speed, so the maximum value of the welding current occurs at the moment when the welding base metal and the droplet short-circuit, which further accelerates the generation of spatter. This is causing a problem.

As described above, the conventional consumable electrode feeding method for DC welding power sources causes a lot of spatter, which reduces welding efficiency and requires removal of adhered spatter. Spatter adheres to the shield nozzle of the welding torch, obstructing the flow of shielding gas and causing problems such as deterioration of the mechanical performance of the welded part.

In order to improve these problems, the output voltage of the DC welding power source can be lowered before and after the droplets short-circuit to the welded lzL material to reduce the amount of spatter, or the welding current output can be controlled in an analog manner. A method was proposed to reduce the amount of spatter generated. for example,
JP-A No. 60-130469, JP-A No. 10-1452
No. 77, JP-A-60-145278 Kano, JP-A-60-
1:l:1977.

However, the above proposal requires a complicated electric circuit, and the short circuit time and welding development time are 73 to 10 (m) per time.
sec), it is necessary to speed up the output response of the DC welding power source, which requires, for example, an inverter power source using transistors and a corresponding control circuit, which is likely to become increasingly complicated.

(Problems to be Solved by the Invention) In view of the above-mentioned problems, the present invention instantly stops the feeding of the consumable electrode at the moment when the consumable electrode short-circuits to the welding base material, thereby keeping the amount of spatter generation to a minimum. The present invention also provides a method for controlling the feed of a consumable electrode in a DC welding device, which is a simple control method that allows a flat bead shape to be obtained.

(Means for Solving the Problems) The gist of the present invention is to provide a short-circuit transfer arc welding method in which short-circuits and arcs are not repeated between a consumable electrode and a welding base material.
A DC welding device characterized in that the feeding of the consumable electrode is stopped by detecting a change in the welding voltage or the welding current at the moment when a short circuit occurs, and the feeding of the consumable electrode is restarted when arcing occurs again. (This is in the electrode feeding control method.

The present invention will be explained below.

(Function) Figure 1 shows an example of the configuration of a control device that performs the feeding control method for consumable polarization in the above-mentioned DC welding device, and shows the configuration of a control device that performs the feeding control method for consumable polarization in the above-mentioned DC welding device. 13, the 'PI contact current (/j is connected to the detection circuit 7, the output of this detection circuit 7 is connected to the differentiating circuit 10, 4 the output of this differentiating circuit io,...!, Ii from the quasi-circuit 9 The output terminal of the comparison circuit 8 is input to the amplifier 11, and the output terminal of the comparison circuit 8 is input to the amplifier 11.
The output terminal of this amplifier 11 is connected to the brake sealing circuit 12 for the consumable electrode feeding motor, and is also connected to the DC welding power source 6.
Between the consumable electrode feed motor 4 and the consumable electrode feed motor 4, a cutoff circuit 12 for the consumable electrode feed motor river brake is connected.

Next, the operation of the above control device will be explained.

Welding voltage and welding current are supplied from the DC welding power source 6 between the consumable electrode 1 and the welding base material 3, and short circuits and arcing are alternately repeated between the consumable electrode 1 and the welding base material 3, and the consumable electrode Ceremony arc welding is performed.

The detection circuit 7 uses the welding voltage value generated by the arc 2 or the welding current value generated by the shunt 13 as an input signal source to check whether the connection between the consumable electrode 1 and the welding base material 3 is due to a short circuit or a re-arc. , the relationship between this change in output and time is sensitively detected by the differentiating circuit 10 to minute changes in the input signal, and the signal is outputted instantaneously to approximately serve as a predictive signal, which is compared to the signal from the reference circuit 9 by the comparing circuit 8 to 0N. -OFF signal output, and this signal is output to the amplifier circuit 11.
The output voltage is amplified by the consumption voltage, and the switching circuit 12 with a brake for the consumable quasi-pole feed motor is operated. When no signal is input from the amplifier 11 to the consumable electrode feed motor switching circuit 12 with brake, the output power from the DC welding power source 6 becomes an electric circuit connected to the consumable electrode feed motor 4, and the consumable electrode feed motor 4 is connected to the consumable electrode feed motor 4. The electrode feeding motor 4 is driven.

The consumable electrode l is fed out from the reel 5 by driving the consumable electrode tip motor 4. Further, when the signal from the amplifier 11 is input, the output power from the DC welding power source 6 becomes an electrical circuit that is disconnected, and at the same time, the input terminal of the consumable electrode feeding motor 4 is short-circuited in terms of the electrical circuit. This allows instantaneous stopping without inertia. This instantaneous stop may be achieved by a mechanical brake system, or by turning the consumable electrode feeding motor 4 0N-OFF by an operation of 0 or more.
The feeding speed of the G electrode 1 is made to match the short circuit and re-arc, and the feeding is performed intermittently.

As mentioned above, the unreleased II detects the moment when a droplet transfers to the welding base metal and causes a short circuit, and cancels the delay in the consumable electrode feeding stop time using a prediction signal from the differential circuit, so that the consumable electrode will be consumable when the short circuit actually begins. Since the feeding of the electrode is stopped, the droplets remain small and stably fall off from the consumable electrode and transfer to the welding base metal, so the occurrence of spatter is extremely reduced.

Furthermore, even if spatter occurs, the particle size of the spatter is small, so the heat capacity t4 is small, and it does not adhere to the surrounding welding base metal or welding torch, improving workability and gas shielding properties. The waveforms of the welding current and welding voltage at this time are shown in FIG.

(Example) The fluctuation pattern 18 of the welding voltage value and welding current value when short circuit and arc are repeated in the conventional method υ is, for example, downward butt position, C02 gas shield, wire diameter 1.2 (mmφ)
When the welding conditions are set to 30 (V) and 200 (A), the waveform becomes as shown in Figure 3, and the welding conditions are 10 to 20 (V).
), the fluctuating waveform had a width of about SO~10G(A), but according to the method of the present invention, the waveform as shown in Fig. 4 was fluctuating.
In(V), the fluctuating waveform tonality with a width of about 10 to 30(A), and the amount of spatter deposited on the welding torch have been reduced to a local to patchy level compared to the conventional welding torch.

(Effect of Issue 11) As explained above, in the present invention, in the consumable electrode type arc welding method in which short circuit and arc generation are alternately repeated between the consumable electrode and the weld base metal, a circuit detects the moment when a droplet short circuits. By stopping the feeding speed of the consumable electrode using a differential circuit, the droplets formed at the tip of the consumable electrode are stably transferred to the welding base metal while remaining small, resulting in less spatter and less spatter. Since the particle size of the spatter is small, it has a small heat capacity, does not adhere to welding torches, etc., and does not affect gas shielding properties, so there are no defects in the welded area, and welding workability has been improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a control device that performs a consumable electrode feeding control method in a DC welding apparatus of the present invention, and FIG.
Figures (a) to C1) are diagrams showing the process of droplets transferring to the consumable electrode or the welding base metal, Figure 3 is a waveform diagram of welding current and welding voltage when using a conventional DC welding device, and Figure 4 The figure is a waveform diagram of welding current and welding voltage when the consumable electrode feeding control method in the DC welding apparatus of the present invention is performed. 1... Discharge 1L electrode, 2... Arc, 3... Welding base material. 4...Consumable electrode feeding motor, 5...Consumable electrode reel, 6...DC welding power source, 7...Detection circuit, 8...
Comparison circuit, 9-), % half circuit, 10-...differentiation circuit, t
i-... Amplifying circuit, 12... Cutting circuit with brake for consumable electrode feeding motor, 13... Shunt, l 4-...
Droplets, 15-... spatter.

Claims (1)

[Claims] In a short-circuit transitional arc welding method in which a short circuit and an arc are repeated between a consumable electrode and a welding base metal, a change in the welding voltage or welding current is detected at the moment a short circuit occurs and the feeding of the consumable electrode is stopped, A method for controlling the feeding of a consumable electrode in a DC welding device, characterized in that the consumable electrode is fed when a re-arc occurs.