RU2193454C2 - Device for application of coats on outer surfaces of articles - Google Patents

Abstract

FIELD: metallurgy; mechanical engineering; aeronautical and space engineering, transport, oil and gas producing industry, power engineering. SUBSTANCE: proposed device is provided with swivel unit mounted in spraying head body for turning the flow at angle of 90 deg. towards longitudinal axis of symmetry of head. Swivel unit is communicated and engageable with outlet of supersonic annular nozzle; swivel unit is circular and axisymmetric relative to central longitudinal axis of head. Device forms two-phase gas mixture (particles?carrier) possessing required thermal and gas-dynamic parameters to ensure technology of forming high-quality coats. EFFECT: improved quality of coats; increased productivity at required thickness irrespective of profile of articles. 2 dwg

Description

 The invention relates mainly to the metallurgical industry, but can be widely used in other sectors of the national economy, such as engineering, aviation, astronautics, transport, oil and gas industry, power plants, etc.

 A number of coating devices are known comprising a powder dispenser-feeder with a hopper for containing powder and working gas supply channels (A.S. 1138429, class C 23 C 4/00, 1983). In the known device the flow rate of low-flowing, microdispersed powders is not stabilized, which did not allow the organization of a controlled process.

 A device for coating is known, comprising a mixing chamber with a supersonic nozzle, a hopper for filling powder with a powder metering feeder and a working gas supply system (A.S. 1618778, class C 23 C 4/00, 1991).

 The known device does not provide acceleration of the powder mixture to the required level of speeds, providing the formation of coatings with specified mechanical and physico-chemical properties that are identical over the entire surface of the part.

A coating device is known, comprising a hopper for loading a powder mixture with a metering feeder, a gas supply system to the metering feeder, a mixing chamber, a spray head associated with the mixing chamber. This device differs from others in that the feeder-dispenser is made in the form of a supersonic feeder-ejector, and the powder spraying head is made in the form of an annular collector - an annular supersonic nozzle (Patent of the Russian Federation 2089665 from 06.23.95 on “Coating device”),
The known device is designed to implement a new low-temperature gas-dynamic method (NTGDM) coating (Patent of the Russian Federation 2082823 from 06/17/91 on "Method for producing coatings").

 The known device forms coatings on the external surfaces of parts, however, due to the peculiarities of its circuit, it does not allow the use of the optimal, required, calculated ratio of the mass flow rate of the carrier gas and the powder mixture.

 The aim of the invention is to improve the quality of coatings and increase the productivity of the technological process of applying multifunctional coatings on the outer surface of products of various configurations with their longitudinal broach along the axis of the spray head.

This goal is achieved by the fact that the device for coating the low-temperature gas-dynamic method, containing a hopper for loading the powder mixture with the feeder-dispenser, a mixing chamber, a system for supplying working gas to the mixing chamber and a feeder-dispenser, a spray head, in the housing of which there is a collector with an annular supersonic nozzle. At the same time, a rotary device is located in the housing of the spray head, which ensures rotation of the flow at an angle of 90 ^o towards the longitudinal axis of symmetry of the head. The rotary device is communicated and associated with the output of a supersonic annular nozzle. It has the shape of a ring and is made axisymmetric with respect to the central longitudinal axis of the head.

 Figure 1 shows a diagram of the proposed device for coating on the outer surface of the part, and figure 2 is a diagram of the spray head.

 The coating device consists of a hopper 1 for loading a powder mixture prepared in a certain ratio of component-powders; supersonic ejector-feeder 2, sampling the necessary for coating the mass flow of the powder mixture from the hopper 1; mixing chamber 3, connected with the spray head 4 and through the feeder-ejector 2 with the hopper 1.

 The spray head (Fig. 2) is an annular collector 5 connected to a supersonic annular longitudinal nozzle 6, which is necessary for the formation of a two-phase supersonic flow, its acceleration to the required speed and delivery using the rotary device 7 to the surface of the part where the coating is applied.

 The geometric dimensions of the collector and the nozzle profile are calculated on a computer taking into account friction and heat transfer along the length of the nozzle path and the rotary device.

 For the formation of a two-phase mixture in the desired ratio of the mass of particles and carrier gas, as well as the delivery of this mixture to the manifold 5 (Fig. 2) of the nozzle, the device contains two pneumatic systems: a supply system to the mixing chamber 3 (Fig. 1) of the working carrier gas 8 and a gas supply system 9 for operating the feeder-ejector 2. Both systems are connected to a battery of receivers 10 for storing compressed gas.

 The working gas supply system 8 includes: a pressure reducer, a pressure gauge, a check valve, a heater, a thermocouple (not shown in Fig. 1) and a mixing chamber 3. The gas supply system 9 for operation of the ejector feeders 2 includes: a pressure reducer, a check valve, and shut-off valves valves, pressure gauge (not shown in Fig. 1).

 The proposed device for coating works as follows.

 The device can produce coating on the external surfaces of the part, products of rolling mills, fittings, etc. both independently and during the technological process of manufacturing products (pipes, corners, channels, etc.).

 The spray head 4 of the device is installed so that the axis of the annular collector 5 and the nozzle 6 coincide with the axis of the product (pipe, angle, channel, etc.) passing through the longitudinal nozzle.

 The speed V of the broaching part can be equal to the speed of manufacture in the process (for example, on a rolling mill).

 The coating material (powder) is selected depending on the purpose of the coating (anti-corrosion, heat-resistant, wear-resistant, etc.).

 As the coating material can be used metals, alloys of metals, ceramics, cermets (carbides, borides, etc.). The diameter of the powder particles is determined by the density of the powder material and can vary in a wide range - from several microns to several tens of microns.

A mixture of gas and powder is formed in the pneumatic systems 8 and 9 of the device and with the necessary thermodynamic parameters enters the annular collector-mixer 5 (Fig. 2) of the spray head 4 (Fig. 1). The two-phase mixture, entering the annular collector 5 (Fig. 2), moves along the design profile of the supersonic nozzle 6, accelerates, acquiring the design speed at the entrance to the rotary device 7. By changing the speed vector in the rotary device by 90 ^o in the direction to the part axis, two-phase the flow reaches the surface of the part and forms a coating. The calculated final particle velocity in a two-phase flow is determined by the type of coating, and the mass concentration of particles in the flow by coating thickness, speed V of the movement of the part along the axis of the nozzle, and dimensions of the part (for example, diameter).

 The mass flow rate of the powder consumed uniquely determines the mass flow rate of the carrier gas.

 The temperature level of the two-phase flow, which determines the speed of the working gas and powder particles at the exit of the nozzle, is set by the kind of coating and much lower than the melting temperature of the material of the powder particles is selected.

 The mass flow rate of the powder passing through the supersonic feeder-ejector 2 (Fig. 1) is determined by the parameters of the compressed gas at the inlet of the ejector, which is continuously regulated by the gas supply system 9. The two-phase mixture formed in the feeder-ejector 2 enters the mixer 3 (Fig. 1) for mixing with the carrier gas, it is further transported to the annular manifold 5 (FIG. 2) of the spray head.

 The proposed device creates a two-phase gas mixture (particles + carrier gas) with the necessary thermo- and gas-dynamic parameters, providing the technology of coating formation and its quality.

 The device allows to obtain a uniform, predetermined thickness coating over the entire external surface of the product, without rotation, while the surface profile of the product can be of any shape (cylinder, polyhedron, channel, angle, fillet, etc.).

Claims (1)

A device for applying coatings to the outer surfaces of products, containing a hopper for a powder mixture with a metering feeder, a mixing chamber, a system for supplying working gas to the mixing chamber, and a metering feeder, a spray head, in the housing of which a collector with an annular supersonic nozzle is located, characterized in that it is provided inside the housing a rotary head device to allow the flow rotation angle of 90 ^o in the direction of the longitudinal axis of symmetry of the head, and reported a yield of conjugate to supersonic tsevogo nozzle and configured annular and axially symmetrical relative to the central longitudinal axis of the head.

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