RU2672961C2 - Electric arc plasmotron - Google Patents

Abstract

FIELD: plasma processing technology.SUBSTANCE: invention relates to the products plasma processing technology, and more specifically to the electric arc plasmatrons intended for the powder materials spraying, including high-melting metals. Arc plasmatron comprises housing, a nozzle, an anode electrode, carrier gas with metallized powder supply unit, active medium supply unit through the nozzle conical channel, in which the plasma-generating channel is formed between the nozzle cone-shaped output channel and the surface to be welded. Nozzle cone-shaped output channel is rigidly connected to the straight section and the cone-shaped input channel, inclined relative to the axis and generatrix channels, to which to the carrier gas with the metallized powder direct supply channel and the active medium supply channel are connected. Anode electrode is connected to the nozzle body outer surface, and on the plasmatron body a working handle is located at an angle.EFFECT: technical result consists in increase in the efficiency, power density and reliability, in the plasmatron design and operation simplification.1 cl, 3 dwg

Description

The invention relates to technology for plasma processing of products, and more specifically to electric arc plasmatrons designed for spraying powder materials, including refractory metals. Spraying is performed on the surface of products in order to obtain coatings for various functional purposes.

Currently, various types of electric arc plasmatrons have been created, which serve to spray coatings on the surface of products and materials. In the process of plasma spraying, the particles of the powder material are melted and accelerated in the plasma stream, after which they are deposited on the prepared surface in the molten state.

Known two-electrode plasmatrons containing a cathode and anode in the form of a nozzle. In such plasmatrons, the arc length is less than or equal to the length of the self-aligning arc. Plasmatrons of this type generate a short electric arc, so currents of more than 200A are required to obtain high-quality coatings. At lower current values, plasmatrons of this type do not provide the required heating and acceleration of powder particles due to insufficient energy input into a short arc. The required temperature of the plasma flow can be achieved only by increasing the arc current, however, in this case, erosion of the electrodes increases. An increase in plasma temperature also leads to intense evaporation of small particles, as a result of which the quality of the applied coatings is significantly impaired. (Plasmatrons: designs, characteristics, calculation / A.S. Koroteev, V.M. Mironov, Yu.S. Svirchuk. - M.: Mechanical Engineering, 1993. - 296 p.).

The disadvantage of this device is the excitation of a short electric arc, so currents of more than 200A are required to obtain high-quality coatings.

Plasmatrons are also known in which stabilization of the arc discharge is ensured by supplying a stabilizing medium through tangential channels into the interelectrode gap. The channels for supplying a stabilizing medium are in communication with a conical channel formed between the opposite surfaces of the sections of the interelectrode insert (see, for example, US Pat. No. 6,430,070, IPC B23K 10/00, published on November 19, 2002).

The disadvantage of this device is the complex design of the plasma torch and low productivity.

The present invention is aimed at increasing the duration of the working state of an open plasma, simplifying the design of the plasma torch and increasing its productivity.

This is achieved by the fact that it provides a direct supply under pressure of a transporting gas with metallized powder to the inlet conical channels and a straight section, acceleration of the powder particles by supplying the active medium to the inlet conical channel. In addition, the active medium (heated aerosol-conducting liquid with the addition of combustible material, for example, water with a content of 10% gasoline). This aerosol increases the breakdown distance between the electrodes, ignites and burns by providing oxygen insulation, heats the substrate and the sprayed powder, and stabilizes the plasma formed by the electric arc.

In FIG. 1 shows a top view of an electric arc plasmatron device; FIG. 2 is a side view, in FIG. 3 scheme of the device.

An arc plasma torch for spraying coatings comprises a housing 1 (Fig. 1), a nozzle 6 (Fig. 1), an anode electrode 4 (Fig. 1), a conveyor gas supply unit with metallized powder, an active medium supply unit for spraying through the cone-shaped channel of the nozzle, in addition, the plasma-forming channel 10 (Fig. 3) is formed between the output cone-shaped channel of the nozzle 5 (Fig. 1) and the weld surface 11 (Fig. 3), in turn, the output cone-shaped channel of the nozzle 5 (Fig. 1) is rigidly connected to the straight section 8 (Fig. 2) and the conical inlet anal 3 (Fig. 1), inclined with respect to the axis and forming channels 12 (Fig. 3) with which the channel for direct supply of conveying gas is connected with metallized powder 2 (Fig. 1) and the channel for supplying the active medium 7 (Fig. 1), except In addition, the anode electrode 4 (Fig. 1) is connected to the outer surface of the nozzle body 6 (Fig. 1), and the working handle 9 is angled on the plasma torch body (Fig. 2).

The device operates as follows. Before turning on the plasmatron, the supply system pipe, to the active medium supply channel 7 (Fig. 1), the hoses of the active medium supply system, to the anode electrode 4 (Fig. 1) are connected to the nozzle of the channel for direct supply of conveying gas with metallized powder 2 (Fig. 1) ) cable from the power source.

When you turn on the plasmatron, the cathode from the power source is connected using switching elements (not shown) to the weld surface 11 (Fig. 3). The discharge current is not more than 50A. Ignition of an arc discharge in a plasma-forming channel, 10 (Fig. 3) between the outlet cone-shaped channel of the nozzle 5 (Fig. 1) and the weld surface 11 (Fig. 3), is carried out after it is filled with a transporting gas with metallized powder and the channel is a plasma-forming active medium.

The supply of conveying gas with metallized powder is carried out through the axial channel of the direct supply of conveying gas with metallized powder 2 (Fig. 1). Further, into the inlet conical channel 3 (Fig. 1), the straight section 8 (Fig. 2) and through the cone-shaped channel of the nozzle, into the plasma-forming channel 10 (Fig. 3), formed between the outlet cone-shaped channel of the nozzle 5 (Fig. 1) and the weld surface 11 (Fig. 3).

The plasma-forming active medium is supplied through the axial channel 7, radial channels 12, providing vortex swirling of the active medium. Next, the plasma-forming active medium is fed into the cavity of the inlet cone-shaped channel 3 (Fig. 1), the direct section 8 (Fig. 2) and through the cone-shaped channel of the nozzle, into the plasma-forming channel 10 (Fig. 3) formed between the outlet cone-shaped channel of the nozzle 5 ( Fig. 1) and a weld surface 11 (Fig. 3). The supply under pressure of the active medium accelerates the movement of the metallized powder, in addition, having a conductivity and combustibility, this medium supports the burning of an electric arc. The plasma torch length changes depending on the parameters of the active medium.

After ignition of the arc discharge in the plasma-forming channel, a flow of transporting gas with metallized powder intended for spraying is supplied to a predetermined region of the initial arc section (to the cathode zone). Preliminary mixing of the transporting gas with the powder is carried out in the system for the preparation and supply of the working mixture (not shown in the drawing), which is connected to the channel for the direct supply of transporting gas with metallized powder 2 (Fig. 1). All pipelines and housing 1 are made of dielectric material. Details of the nozzle 6, the inlet cone-shaped channel 3 (Fig. 1) are made of alloyed metal.

The optimum mode for introducing the powder into the plasma-forming channel is achieved by controlling the flow rate of the transporting gas, the plasma-forming active medium, and the selection of the nozzle passage size.

The presence of distinctive features leads to increased efficiency, specific power and reliability, simplification of the design and operation of the plasma torch with MEW. The specified plasmatron can be used in plasma spraying and hardening plants.

Claims (1)

An electric arc plasma torch for spraying coatings, comprising a housing, a nozzle with an anode electrode fixed to it, a transport gas supply with metallized powder for spraying located at the rear of the housing, and a cathode electrode, characterized in that a two-stage groove is made in the front of the housing the first protrusion of which the extruder is rigidly fixed with fittings for supplying the active medium, forming a channel for the active medium with the second protrusion of the housing, while in the interior of the extruder with Rhone its front portion is screwed into the inner nozzle, to the outer part of the extruder nozzle is screwed with mounted thereon the anode electrode and the cathode electrode is configured to be attached to the sprayed surface of the part.

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