RU2201864C2 - Device for abrasive heat treatment of part surfaces - Google Patents

Abstract

FIELD: mechanical engineering. SUBSTANCE: invention can be used at preparation of surfaces for painting. Mounting unit is secured in housing from side of abrasive material feed. Nozzle unit to pass air-abrasive flow is secured in housing at its outlet. Abrasive material feed tube is arranged inside combustion chamber being passed through central hole swirler. Swirler is made in form of screw with fuel holes. Combustion chamber is formed by inner surfaces of flue tube and nozzle unit. Air feed duct is arranged in housing between wall of housing and wall of combustion chamber, being secured by one end on end face surface of mounting unit, and by other end with radial holes, on nozzle unit. Coaxial holes made in housing wall and in mounting unit accommodate needle fuel valve for communication with fuel holes of screw. Said valve is coupled with fuel feed union through fuel feed ball valve, gauze filter and fuel jet. Air feed union is secured on housing diametrically opposite to needle fuel valve. Such design increases speed of air-abrasive material flow at moment of its ejection to surface to be cleaned owing to acceleration and swirling by products of combustion of heavy hydrocarbon fuel inside combustion chamber. EFFECT: improved quality of preparation of surface for painting. 2 cl, 1 dwg

Description

 The invention relates to the field of abrasive surface treatment and can be applied in various sectors of the economy related to paintwork in preparing surfaces for painting.

 Known devices for cleaning surfaces for painting, consisting of a grinding wheel or mechanical brushes and drive them to move on the work surface (1).

 The disadvantage of these devices is the low productivity of cleaning large areas, as well as the inconvenience arising from cleaning places of angular joints of structures due to the formation of "dead" zones.

 A device for abrasive processing, comprising a housing, a ceramic guide insert and a clamping nut, is known. The abrasive mixture in this device is supplied by a stream of compressed air through a nozzle (2).

 However, the known device does not allow to remove from the surface some types of contaminants, such as fatty, acidic, alkaline, etc., which degrades the quality of the coating applied in the future.

 A device for thermoabrasive processing is known, comprising a burner for feeding abrasive material into a jet of high speed flame (3).

 The disadvantage of this device is poor-quality preparation of the fuel mixture before ignition, since its formation occurs in the sleeve of the combustion chamber, where the liquid fuel and gaseous oxidizer enter separately, which makes it difficult to start the device and affects the stabilization of combustion of the fuel mixture.

 Closest to this invention is a known device for thermoabrasive machining of surfaces of parts, comprising a housing with fittings for supplying liquid fuel and a gaseous oxidizer, a mounting unit mounted in the housing on the supply side of the abrasive, a nozzle unit for the outflow of a high temperature jet, mounted in the housing on the side of the flow outlet aerosol mixtures, a combustion chamber with through radial holes located inside the housing, an abrasive feed pipe placed inside the combustion chamber and missing through the central hole of the swirler installed in the combustion chamber from the inlet side of the air mixture flow (4).

 However, this device has a low productivity due to the low speed of the expiration of the air-abrasive stream at the time of discharge to the surface to be cleaned.

 The objective of the invention is to increase the rate of expiration of the air-abrasive stream at the time of ejection to the surface to be cleaned by accelerating and twisting it in the longitudinal direction by the combustion products of heavy hydrocarbon fuel inside the combustion chamber.

 To solve this problem, in a device for thermoabrasive surface treatment of parts, comprising a housing with fittings for supplying liquid fuel and a gaseous oxidizing agent (for example, air), a mounting unit mounted in the housing on the supply side of the abrasive, a nozzle block for the expiration of the air-abrasive stream, fixed in the housing from the side of its outlet, a combustion chamber with through radial holes located inside the housing, an abrasive feed pipe located inside the combustion chamber and passed through the main the opening of the swirl installed in the combustion chamber from the inlet side of the air-abrasive flow, the swirl is made in the form of a screw with fuel holes and guide channels for a gaseous oxidizer, and the device is equipped with a flame tube, the inner surfaces of which and the nozzle block form a combustion chamber, an air supply path with through radial holes made at one end thereof, a nozzle insert fixed in the nozzle block, a needle fuel valve for regulating the fuel supply , a ball valve for supplying fuel, a mesh fuel filter and a fuel nozzle, while the air supply path is placed in the housing between the wall of the housing and the wall of the combustion chamber and at one end is fixed to the end surface of the mounting unit, and the other end with radial holes to the nozzle block, in in the wall of the housing and in the mounting unit, coaxial holes are made in each, in which a needle fuel valve is mounted with the possibility of communication with the fuel holes of the screw and connected to the fuel supply fitting through the ball valve n supply fuel strainer and the fuel jet and the air supply nozzle is mounted on the body diametrically opposite to the fuel needle valve.

 Due to this design of the device, the process of forming the fuel-air mixture by the screw is carried out directly in the combustion chamber. Compressed air leaving the auger, which has a targeted spiral-tangential movement with respect to the flow of the air-abrasive mass, uniformly and finely disperses the fuel coming from the auger’s fuel channels along the length of the combustion chamber, thereby creating favorable conditions for fuel combustion. In this process, additional energy is created during combustion, which appears during the spiral-shaped rotating combustion of the fuel-air mixture, which directly affects the acceleration and swirling of the air-abrasive stream.

 The drawing shows a device for thermal abrasive processing, cross section.

 The device comprises a fitting 1 for supplying an air-abrasive stream screwed by means of a threaded connection into a mounting unit 8 welded to the housing 15. An abrasive supply pipe 10 is screwed onto the mounting unit 8 from the opposite side and attracting screw 9 to the mounting unit 8. To the end the surface of the mounting unit 8, located inside the housing 15, by means of a welded joint, an air supply path 14 having through radial holes in the area of connection with the nozzle block 12 is welded. In the nozzle block 12 a nozzle insert 13 is inserted, which is pressed against it by a clamping nut 16. A heat pipe 11 is screwed onto the nozzle block 12. A fuel needle valve 7 is screwed into the mounting unit 8 through a radial hole made in the end part of the housing 15, the housing of which is hermetically welded to the housing of the device 15. The fuel needle valve 7 is threadedly connected to the fuel supply ball valve, a fuel nozzle is installed between them 6. A fuel filter 5 is inserted on the opposite side of the fuel supply ball valve 4 and screwed in by means of a threaded connection, fitting 3 for supplying fuel. In the housing 15, a radial hole is made diametrically opposite to the attachment point of the needle fuel valve 7, to which, through a welded joint, a nozzle 2 for supplying a gaseous oxidizer, for example, air, is attached.

 A device for thermal abrasive processing works as follows. As a combustion initiator, the ignition dose of hydrocarbon fuel with a large number of light fractions, for example, gasoline, is poured into the combustion chamber formed by the internal surfaces of the nozzle block 12 and the flame tube 11 through a hole in the nozzle insert 13. When organizing a pulsating flow of compressed air through the nozzle 2 of the air supply with short time intervals, gasoline vapors that are ignited by an open flame, due to the formation of a rarefaction zone inside the combustion chamber and the prevalence of the combustion velocity of the flame front propagation over the rate of expiration of gasoline vapors from the nozzle hole, enter inside the combustion chamber and ignite the main ignition dose of gasoline. After the ignition of gasoline opens ball valve 3 of the fuel supply. Heavy hydrocarbon fuel - diesel fuel under excessive pressure enters through the fuel strainer 5, the fuel nozzle 6, the fully open needle fuel valve 7, passes through the fuel holes in the screw 9, enters the combustion chamber and, being mixed with burning gasoline vapors, ignites. At the same time, through the air supply nozzle 2, the air supply path 14, the hole in the flame tube 11 and the guide channels of the screw 9, compressed air enters the combustion chamber at constant pressure, providing the necessary stoichiometric ratio of fuel to air to ensure combustion. The combustion products are released into the environment through the nozzle block 12 with the nozzle insert 13, receiving lateral swirling due to the organization of air supply by the screw 9. When the combustion mode is established, by adjusting the amount of fuel supplied to the combustion chamber, a smokeless operation mode is established by the needle fuel valve 7. After making the necessary adjustments related to combustion, an air-abrasive mass is fed into the combustion chamber through the nozzle 1 for supplying an air-abrasive flow, pipe 10 for supplying abrasive material, which is twisted in the longitudinal direction and receives additional acceleration passing through the nozzle block 12 and the nozzle insert 13 due to the emission of combustion products of heavy hydrocarbon fuel-diesel fuel into the atmosphere under the action of overpressure forces.

 Due to the fact that the pipe 10 is located at the beginning of the narrowing of the conical part of the nozzle block 12, it is possible to affect the air-abrasive flow with the combustion products of the fuel-air mixture and thereby acceleration and its unwinding.

 The nozzle block 12 is made according to the scheme — a tapering conical part with a cylindrical critical part, which makes it possible to increase the accuracy of the spot of air-abrasive flow on the treated surface with a slight loss of speed when it flows out of the nozzle.

 The use of a replaceable nozzle insert of a heat-resistant material, for example, boron carbide, allows to increase the durability of the nozzle block and the device as a whole.

A device made according to the invention provides:
- cleaning surfaces of large-sized metal and concrete structures from corrosion products, dirt and worn coatings under the application of new protective coatings;
- removal of scale before applying protective coatings in the manufacture of new metal structures;
- cleaning the bottoms of ships from fouling, old paint and corrosion products;
- cleaning of structures and structures made of natural stone and concrete to update their surfaces;
- removal of cement film and the destroyed concrete layer during the restoration of structures made of concrete and reinforced concrete.

 When using this invention, the processing quality is significantly improved while increasing productivity by 8-10 times. In this case, the specific costs per unit area of the cleaned surface of the abrasive material are lower by 3-4 times, and compressed air by 8-9 times.

Sources of information
1. SU 1101538, 07/07/1984, column 2, line 40-50.

 2. SU 1218053, 07/07/1984.

 3. US 4384434, 1983.

 4. WO 88/05711, 08/11/1988.

Claims (2)

 1. A device for thermo-abrasive surface treatment of parts, comprising a housing with fittings for supplying liquid fuel and a gaseous oxidizer, a mounting unit fixed to the housing on the abrasive supply side, a nozzle block for exhausting, and a chamber located inside the housing, mounted on the outlet side of the air-abrasive stream combustion with through radial openings, in which a swirler is installed on the inlet side of the air-abrasive flow, through the central opening of which a feed pipe is passed an abrasive, characterized in that it is equipped with a flame tube, an air supply path with through radial holes at one of its ends, a nozzle insert fixed to the nozzle block, a fuel needle valve, a liquid fuel supply ball valve, a mesh fuel filter and a fuel nozzle, while the combustion chamber is formed by the inner surfaces of the flame tube and nozzle block, the swirl is made in the form of a screw with fuel holes, the air supply path is placed between the wall of the housing and the wall of the chamber of combustion and with one end mounted on the end surface of the mounting unit, and the second with through radial holes, on the nozzle block, coaxial holes are made in the housing wall and in the mounting unit, in which a fuel needle valve is connected with the fuel holes of the screw connected to the a nozzle for supplying liquid fuel through a ball valve for supplying fuel, a strainer and a fuel nozzle, and a nozzle for supplying a gaseous oxidizer is mounted on the housing diametrically opposite the needle top drain valve.  2. The device according to claim 1, characterized in that air is used as a gaseous oxidizing agent.