UA35485A - injector of electrometallization device - Google Patents

Abstract

The invention relates to the equipment for spraying metallized coating on sheet and profile rolled products, tubular metal structures and pipes, and also on the surfaces of the machine parts and mechanisms. An injector of electrometallization device contains nozzle for supply of air, leads with electrode wires, axes of which lie in one plane and cross beyond the limits of leads.

Description

The invention belongs to the equipment for spraying a metallization coating on sheet and profile rolled steel, tubular metal constructions and pipes, as well as on the surface of parts of machines and mechanisms.

There is a well-known design of a device for applying an electroplating coating, which contains two electrodes that are fed at an angle to each other with an electric discharge at the point of intersection, an air nozzle is placed between the electrodes (symmetrically to them), the axis of which passes through the point of intersection of the electrodes (see book " Powder metallurgy and powder coating". - M.: Mashinostroenie, 1987).

In this design, when the spraying gas jet flows around the electrodes, there are a number of negative consequences that lead to a decrease in the quality of the sprayed coating.

Due to the impossibility of a direct impact of the spraying jet on the melting point of the electrodes (crossover point), since the latter are in the path of the gas flow, stagnation zones are observed on the surface of the electrodes, from which the evacuation of the molten electrode metal is difficult. This leads to an increase in the diameter of the sprayed particles, which worsen the conditions for the formation of a high-quality coating.

When the spraying jet collides with the electrodes, intense turbulence of the flow occurs, which is accompanied by a loss of kinetic energy, which leads to a strengthening of the degree of growth of the dynamic pressure of the gas jet in the area where the molten metal is evacuated.

Coatings formed under the described conditions are characterized by insufficiently high adhesion strength and density. The density of coatings is of particular importance when using coatings to protect metals from corrosion.

The closest in technical essence to the proposed invention is a.s. USSR Mo 308103 С23С 71/00 "Spraying head of an electrometalizer", which contains a housing with air and current leads for electrodes placed in it, the axes of which lie in the same plane and cross outside the current leads, current arresters and an air nozzle inclined to the axis of the head, made in in the form of a tube bent at an angle, which serves as an extension of the main air nozzle and a torch cutter of sprayed metal.

In the known device, the atomizing jet upon contact with the electrodes undergoes intense turbulence, which leads to significant losses of kinetic energy of the jet, strengthening of the flight speed of metallization particles and the formation of stagnant zones at the point of intersection of the electrodes.

As a result, the conditions for evacuation and dispersion of molten metal from these zones worsen, and the fraction of particles with a diameter of 100 microns prevails in the metal air jet, which negatively affects the strength of the sprayed coating. In addition, the spray jet, which is formed in this spray head as a result of the mixing of the two streams that flow from the main and inclined nozzle, has a large opening angle. As a result, there is intense braking of the peripheral layers of the jet against the ambient air, which also reduces the speed of the particles and, ultimately, the quality of the coating.

The invention is based on the goal of developing a spraying head of a metallizer in which a new mutual arrangement of structural elements makes it possible to minimize the loss of kinetic energy of the spraying jet, giving the metallizing particles high movement speeds, eliminating stagnant zones, improving the evacuation and dispersion conditions of the molten electrode metal, which will increase the quality sprayed coating.

In order to achieve the set goal in the spraying head of the electrometapizer, which contains a nozzle for supplying air, current leads with electrode wires, the axes of which lie in the same plane and cross the boundaries of the electrical leads, according to the invention, the axis of the nozzle is placed at an acute angle to the plane that passes through the axes electrodes with the possibility of crossing the electrode crossing point with it and with a shift towards the electrode-cathode.

At the same time, the nozzle for air supply is made of a confusor-diffuser profile.

Design features of the proposed spraying head make it possible to directly affect the melting point of the electrodes without obstacles (electrode wires, arc). This ensures maximum use of the energy of the spraying jet and reduces the loss of kinetic energy of the gas flow, which is associated with intense turbulence in the contact zone with the electrodes and, what is especially important, eliminates stagnant zones where the intensity of the impact of the spraying jet on the molten metal of the electrodes is minimized.

Placing the spray nozzle at an acute angle, for example, 65" relative to the plane that passes through the axes of the electrodes at a distance of 7 5 MM to the point of their intersection, makes it possible to intensify the evacuation of liquid metal from the electrodes as much as possible. The liquid metal layer on the end of the electrodes under the influence of the increasing aerodynamic force intensively is removed, improving the heat transfer from the active spots of the electric arc to the electrodes, which contributes to increasing the productivity of the electrometalization process.

Since the melting of the electrode-anode in the process of electrometalization is accompanied by the formation of coarse particles, the displacement of the spraying nozzle by a distance of 7 mm towards the electrode-cathode makes it possible to improve the dispersion conditions of the molten electrode metal. As a result, the granulometric spectrum of the sprayed particles, which characterizes the metal air jet, becomes finer and more uniform, which contributes to the improvement of the quality of the sprayed coating. Sprayed particles with a uniform granulometric composition are captured by a high-speed supersonic jet (Mach number - 1.8) and transported to the sprayed surface. The speeds achieved by the particles make it possible to form coatings with high adhesion strength and minimal density.

The essence of the invention is explained in Fig. 1, which shows the general view of the invention, Fig. 2 - gas spectrograms of atomizing jets: a - known head; 6 - proposed head; fig. 3 - a graph of the dependence of the granulometric composition of metallization particles on the design of the spraying head - serial electrometallizers ZM-12MII),

ZM-17(I), proposed warhead (I). The spraying head of the electrometalizer (Fig. 1) consists of current leads 1 with electrode wires 2,3, the axes of which lie in the same plane and intersect outside the current leads and the nozzle 4 of the confusor-diffuser profile, designed for air supply. Spray nozzle

4 is placed at an angle of 7 65 relative to the plane that passes through the axes of the electrodes at a distance of 7 5 MM to the point of intersection of the electrodes, and shifted towards the electrode-cathode by 7 1 MM.

The spray head works like this. Wire electrodes 2,3, which are supplied with voltage through current leads 1, move to the point of their intersection, where an electric arc is ignited. which melts the electrode metal.

At the moment of arc ignition, atomizing gas is supplied to nozzle 4. The spray jet formed in the nozzle is directed to the center of melting of the electrodes, where it evacuates the molten metal from the electrodes, sprays it into dispersed particles and transports them to the sprayed surface, where the particles form a coating.

This electroplating spray head has been manufactured and tested under laboratory conditions

Azov State Technical University.

АЙ brand wire (99.5 95 АЙ) with a diameter of 2 mm was used as electrodes. Spraying mode parameters: arc current I - 240 - 260 A; voltage Ш - -34 V, distance to the metallized surface Y - -110 mm, spray jet pressure Р - -0.55-0.6 MPa.

With the help of a feed mechanism, the electrodes were moved to the crossing point, where the electric arc was ignited. At the moment of ignition of the arc, spraying gas was supplied to the nozzle under pressure. The formed spray jet was directed into the melting zone of the electrodes. The metal of the electrodes, melted by an electric arc, was sprayed into small particles and transported to the sprayed surface, forming a coating.

Comparative results of coating tests are given in the table.

Interrogative head | Drinking hopovka according to the declared technology of the prototype of the night. decision

A method of surface preparation for tire spraying

Cohesion strength, MPa (by the shear method) 17.5 12.8

Density (in 95 from the density of the original wire) 96 81

Yield strength, MPa in tension 0.57 0.5 in compression 1.47 1.38

As we can see from the obtained results, this invention makes it possible to eliminate stagnant zones, provides metallization particles with high speeds of movement in the metal air jet, improves the evacuation and dispersion conditions of the molten electrode metal, which leads to an increase in the quality of sprayed coatings.

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Claims (2)

1. The spraying head of an electrometalizer containing a nozzle for supplying air, current leads with electrode wires, the axes of which lie in the same plane and intersect outside the current leads, which differs in that the axis of the nozzle is placed at an acute angle relative to the plane that passes through the axes of the electrodes with with the possibility of crossing with it to the crossing point of these electrodes and with a shift towards the electrode-cathode. 2. The spray head according to claim 1, which differs in that the air supply nozzle is made of a confusor-diffuser profile.