RU2451584C2 - Method of welding by three-phase arc - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: proposed method may be used for welding of wear-resistant hardening coats by three-phase arc. Third phase of current source is connected to article in half-cycle opposite that of connecting filler wire. Interval of half-cycles corresponds to that of welding current set by current source frequency. Connection of article and wire allows cathodic cleaning of their surface. Wire and article may be connected in AC half-cycles in both straight and reverse polarity.

EFFECT: welding of materials differing in properties.

2 dwg

Description

The invention relates to the field of welding production and can be used for surfacing with a three-phase arc of wear-resistant, corrosion-resistant and other hardening coatings.

A known method of welding and surfacing with a three-phase arc (Method of welding with a three-phase arc. SU. Patent No. 1798077. Publish. 02.28.1993), which consists in connecting the product to one of the phases of a three-phase arc power source through a filler wire. However, this method does not have the ability to adjust the half-wavelength of the passing current and to rationally clean the product from oxide film due to the use of alternating current, which limits the scope.

There is also known a method of pulsed plasma surfacing (Method of pulsed plasma surfacing. SU Copyright certificate No. 1693808), in which two phases are connected to the electrodes, and the third to the filler wire or to the fused product. The filler wire is fed into the column of a compressed arc of direct action, the product is periodically disconnected from the power source and during this period the filler wire is periodically connected to the power source. This method provides adjustment of the ratio of molten to weld metal. However, this method, selected for the prototype, limits its use due to the difficulty of surfacing of various metals properties. For example, aluminum on steel, and vice versa, steel on aluminum. It is difficult to re-excite working arcs with alternating current, especially when reverse polarity occurs on an aluminum product, which reduces the stability of the process.

The technical result of the proposed method is the expansion of the technological capabilities of the method by connecting the desired polarities to the product and wire using a three-phase arc and better cathodic cleaning of surfaces and dosed heat input.

The essence of the invention lies in the fact that surfacing is a three-phase arc, in which two phases of the current source are connected to non-consumable electrodes and an interelectrode arc is ignited, the third phase is connected to the product or filler wire supplied to the arc pole. When surfacing, the combustion of the interelectrode arc is continuously supported, which ensures the re-ignition of dependent arcs on the product and the wire. The cathodic cleaning of the surface of the filler wire is performed by periodically connecting the third phase to the filler wire in half periods of reverse polarity opposite to the half-periods of periodic connection of the product, and the half-periods of connecting the third phase for the filler wire or product corresponds to the half-time of the welding current specified by the frequency of the current source.

The connection of the wire and the product in half periods of alternating current can be made both for direct and reverse polarity. For example, when surfacing aluminum wire on a steel product, the wire should be connected in half-periods of reverse polarity, which will provide cathodic cleaning of the aluminum wire from the oxide film. At the same time, the product will be connected to the right polarity. This will ensure the unhindered occurrence of the anode spot on the steel part, as It is known that the cathode on a steel part is much more complicated than on aluminum.

The invention is illustrated by drawings, in which Fig. 1 shows an electrical diagram of the inclusion of diodes in a circuit of a wire and a product, Fig. 2 is a flow diagram of currents flowing in a wire and a product when the switch S is turned on in position 1.

1, a power supply 1 is connected to a mains supply Uc. At the source output, the middle phase is connected via VD1 or VD3 diodes to wire 2, and by the extreme phases to two tungsten electrodes 3 and 4 located in the plasma torch 5. The product 6 is connected to the middle phase of the source through VD2 or VD4 diodes. The switch S can be switched to position 1 or 2.

The method is implemented as follows. First, the interelectrode (“standby”) arc is ignited between the non-consumable electrodes 3 and 4 of the plasma torch 5 from the two extreme phases of the welding power source 1. The current supply from power source 1 to wire 2 and article 6 has a branching. When the switch S is turned on in position 1, the positive half-wave of the current passes through the diode VD1 to the wire and its cathodic cleaning is performed, and the negative - through the diode VD2 to the product. When the switch S is turned to position 2, the polarity on the wire and the product changes to the opposite due to the passage of current through the second pair of diodes VD3, VD4.

The inclusion of diodes in the circuit of figure 1 may be the opposite, depending on the technological requirements of welding. For example, with wear-resistant argon-arc welding of aluminum onto steel, the aluminum wire should be connected as the cathode of the working arcs. This will provide cathodic cleaning of the aluminum wire from the oxide film. At the same time, favorable conditions will arise for the appearance of the anode region in the steel product, since in this case cathodic cleaning is not required.

Ensuring the stability of repeated ignitions of dependent arcs on the product and the wire is ensured by the continuous burning of the interelectrode arc of a three-phase torch.

The proposed method can be carried out using known in the art means and materials. As a welding torch, a two-electrode torch with non-consumable tungsten electrodes can be used. As a power source, a well-known three-phase welding power source operating according to the “open triangle” scheme can be used. Obtaining current pulses of the working arcs on the product and wire can be achieved using uncontrolled diode valves used in welding power supply circuits. The filler wire can be fed into the welding zone using conventional feeders of automatic welding machines or semi-automatic machines.

Thus, the proposed method ensures the achievement of a technical result, which consists in expanding the technological capabilities of the method by connecting the required polarities to the product and the wire using a three-phase arc, increasing the stability of burning dependent arcs on the product and the wire, ensuring stable melting of the wire.

The proposed method can be carried out using means known in the art. Therefore, the proposed method has industrial applicability.

Claims (1)

A method of surfacing with a three-phase arc, in which two phases of the current source are connected to non-consumable electrodes and the interelectrode arc is ignited, and the third phase is connected to the product or filler wire supplied to the arc column, characterized in that they maintain continuous burning of the interelectrode arc to ensure re-ignition of dependent arcs between the product and the wire, while performing cathodic cleaning of the surface of the filler wire by periodically connecting the third phase to the filler wire in half periods about inverse polarity opposite half-periods of the periodic connection of the product, and connecting the half-period of the third phase to the filler wire or article corresponds to the half cycle time of the welding current, a predetermined frequency current source.

Images