RU2338638C2 - Method of thermo abrasive treatment and machine "castor" for its implementation - Google Patents

Abstract

FIELD: process.

SUBSTANCE: engine for thermo abrasive treatment contains compressor, vessels for fuel, abrasive and water, jointed to each other, and accelerator. Accelerator contains combustion chamber with fuel injector, bottom, abrasive branch in the form of shaft, jacket, in which it is located supersonic nozzle, additional combustion chamber with tangential holes near by bottom, installed with expansion clearance. Expansion clearance is located according to conditions of providing combustion chamber elongation and coaxial to the last. In bottom it is located fuel branch, outside of which it is located thermo protective envelope and stabiliser. Stabiliser is connected to fuel branch by means of spray injector and ultrasonic dispensers, implemented in the form of bucket. Combustion chamber is with air duct, having cutouts for air and which is connected to jacket. Abrasive branch is installed coaxial and open to supersonic nozzle. Method includes treatment of surface coating by supersonic jet, made of three components: combustion materials, water and abrasive, which are accepted in ratios mentioned in description.

EFFECT: productivity and efficiency improving of surface treatment.

9 cl, 10 dwg, 1 tbl

Description

The invention relates to the field of heat-forming treatment and can be used when applying anti-corrosion coatings on the surface of reservoirs, tanks, bridges, ships, cars, cars, building structures and technological equipment, for cleaning of gumming and viscous coatings, increasing the roughness and improving the decorative properties of various products , as well as to obtain an open texture of concrete and natural stone.

There is a known method of bead-blasting processing and a TARI apparatus for its implementation, in which a two-component jet is formed by the action of an acoustic, vibration of a material nozzle, an increase in the gas pressure drop at its inlet and outlet, while the abrasive particles in the accelerator are accelerated through the transport pipeline in a section 30- 120 of his calibers and sent at an angle of 15-45 ° to the work surface from a distance from the barrel within 35-95 of his calibers [1-3]. In this method, the optimal technological parameters are protected, which improves the cleaning performance, however, the low energy consumption of the jet leads to a low processing speed.

Also known is a method of thermal abrasive blasting [4], for the implementation of which the formation and acceleration of a two-phase supersonic flow is carried out by feeding abrasive and fuel mixed with an oxidizing agent into the combustion chamber, and the other part is fed into the combustion chamber through radial openings. The oxidizing agent enters the burnout zone of the fuel, and the abrasive is fed beyond the mixing zone. A device that implements this method contains a pipeline for abrasive air mixture around which a swirl, a casing, a regenerative tube, a nozzle and a combustion chamber formed by a flame tube with radial openings are located. In the housing, a mixing chamber is made, connected to the fuel supply channel and communicating with the oxidizer channel, and the radial holes in the flame tube are made in the fuel burnout zone and in the mixing zone of the oxidizer with combustion products, while the outlet section of the abrasive pipe is located between the last row of radial holes and the input section of the nozzle, which is made with a cylindrical section, the ratio of the length of which to its diameter is in the range of 4-8. However, this method of preparing a fuel-abrasive mixture involves rapid wear of the air-abrasive pipe and nozzle, since they are not cooled sufficiently and are subjected to intense abrasive wear.

Also known is a method of thermal abrasive treatment of Galchenko [5], in which the processing is carried out by simultaneous thermal and abrasive action, and acceleration and shaping of a two-phase high-temperature flow is carried out by feeding the abrasive into the ignition zone of the fuel mixture in the direction of its movement in the combustion chamber. However, this method provides only the formation of the flow, but there are no technological parameters for surface treatment [6], and most importantly, the supply of abrasive to the ignition zone of the fuel mixture causes intense wear of the supersonic nozzle and, as a result, low life of the device.

Thus, all known methods of thermal abrasive processing improve the essence of preparing a fuel and air-abrasive mixture, however, a common significant drawback is the need to perform eight operations in succession (heating, destruction, removal, increasing the roughness and actual contact area, drying, degreasing, dust removal and activation of the surface layer) , which is a significant reserve in increasing the efficiency and productivity of processing.

A known installation [7], in the receiving chamber of which an abrasive is fed behind the burner nozzle and is dispersed by a high-temperature supersonic flow of combustion products. At the outlet of the ejector, a gas-dynamic accelerator is installed coaxially for accelerating abrasive particles, made in the form of a cylindrical nozzle, the geometric dimensions of which are selected from the conditions for excluding the formation of shock waves inside the accelerator, which inhibit the gas flow. The result is an increase in the reliability and service life of the burner combustion chamber, ensuring a stable supply and an increase in the kinetic energy of the abrasive particles. The effectiveness of the effect of a two-phase jet on the processed material is increased, but the incoming abrasive with air significantly reduces the speed and cools the supersonic flow.

A device for the flame treatment of mineral media [8], which consists of a casing, a distribution head with a fuel pipe and a pipe for supplying abrasive. An air swirl is installed at the inlet to the combustion chamber, and a nozzle for the formation of a high-enthalpy supersonic two-component jet is installed at the outlet. The disadvantage of this device is the low resource of the nozzle in connection with the supply of abrasive material at the entrance to the combustion chamber. In addition, the atomization of fuel is carried out by a jet nozzle, which leads to a low quality of preparation of the fuel mixture, incomplete combustion and, as a result, increased consumption of working components.

Also known is a device for abrasive blasting [9], which consists of a distribution head, a casing, a nozzle for supplying an abrasive, a combustion chamber and a nozzle. The distribution head is made with a screw air swirl, in front of which nozzles for spraying fuel are installed. The pipe for supplying the air-abrasive mixture is made of a ceramic tube and ends in the confuser part of the nozzle. Installing nozzles in front of the air swirl improves the quality of the fuel mixture preparation and allows more efficient use of fuel. Placing the end of the nozzle in the confuser part of the nozzle protects its inner surface from abrasive wear, which slightly increases its service life. However, a significant disadvantage of the device is that the pipe and nozzle are uncooled, as a result of which they are subjected to intense thermal stress. In addition, the design of the nozzle and nozzle are difficult to manufacture and operate.

The device for jet-abrasive surface treatment [10] partially eliminated the above disadvantages. The device consists of a distribution head, housing, material pipe, protective casing with radial openings, a combustion chamber and a nozzle. The protective casing is installed coaxially and with a gap relative to the material pipe, forming an annular channel between them. On the side of the distribution head, this channel is in communication with the air supply pipe, on the opposite side it is plugged with a shoulder. The supply of the device with a casing increases the service life of the material pipe. Compressed air in the coaxial gap cools the material pipe, and then through the rows of radial holes enters the combustion chamber. This creates a wall protective layer that cools the casing from high temperature, and then mixes with gases, participating in the burning of fuel. However, the supply of compressed air to the combustion chamber through the radial holes reduces the temperature and velocity of the high enthalpy jet, which is a significant drawback, as a result of which there is an increased consumption of working components per unit of the treated surface.

A known installation for abrasive machining of a part [11], consisting of a thermoabrasive accelerator, a feeder and a fuel tank, connected to each other and to a source of compressed air. The abrasive feeder contains a distributor and a mixing chamber, which is connected to a device for adjusting the flow rate of the abrasive. The distributor in the lower part is equipped with a pipe for supplying air to the thermoabrasive accelerator, which contains a regenerative pipe and a combustion chamber with radial holes in its wall. One end of the combustion chamber is in communication with a supersonic nozzle, and the other with an air swirl. The execution of the distributor with the pipeline in the lower part allows to reduce the amount of water and oil in the air entering the abrasive feeder and the fuel tank, which increases the reliability of the installation, however, as in the previous device, the mechanism for adjusting and maintaining the mass ratio of the working components is not disclosed.

A device for a combined gas-jet tool is known, comprising a three-channel manifold for transporting fuel, an additional oxidizing agent and a working agent, a combustion chamber, a swirl and a nozzle, and also an annular radial diffuser for supplying fuel to the combustion chamber and creating a protective film on the walls of the combustion chamber by swirling the air flow at the entrance to the combustion chamber [12], however, the proposed device of a gas-jet tool involves an additional supply of oxidizing agent due to the low combustion efficiency Mesi.

The closest technical solution is the device [13], in which the mounting unit is fixed in the housing on the supply side of the abrasive. The nozzle block for the expiration of the air-abrasive flow is fixed in the housing from the outlet side. The abrasive feed pipe is placed inside the combustion chamber and passed through the central hole of the swirler. The combustion chamber is formed by the inner surface of the flame tube and nozzle block. The air supply duct is placed in the housing between the wall of the housing and the wall of the combustion chamber and is fixed at one end on the end surface of the mounting unit, and at the other end with radial holes on the nozzle block. Coaxial openings are made in each wall of the housing and in the mounting unit, 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 a fuel supply ball valve, a strainer and a fuel nozzle. The air supply fitting is mounted on the housing diametrically opposite to the fuel needle valve. Due to this design of the device, the rate of expiration of the air-abrasive stream at the moment of ejection to the surface to be cleaned by accelerating and twisting it with the combustion products of heavy hydrocarbon fuel inside the combustion chamber is increased, however, the abrasive pipeline is short-lived and difficult to manufacture.

Thus, the known methods do not allow with the required performance and efficiency to process surfaces. This can be explained by the lack of indicators of technological processing parameters. Known to us methods give the results of improving the quality of preparation of the fuel mixture and in no invention are not illuminated and specified operations to destroy and remove the surface layer. The proposed devices are characterized by low starting reliability, intense wear of the material pipe and the supersonic nozzle, and most importantly, the high consumption of working components per unit of the treated surface. In this regard, there was a production need to increase productivity and processing efficiency.

The problem can be solved by the proposed method of thermoabrasive processing and a machine for its implementation. The method of thermo-abrasive processing of products includes treating the surface layer with a supersonic jet formed by the combustion products and abrasive supplied to the supersonic nozzle of the accelerator to destroy and remove the surface layer and heat it, while according to the invention, to simultaneously destroy, remove the surface layer, heat it and increase roughness and the actual area of contact, drying, degreasing, dust removal and activation of the surface layer, the latter is heated to 380-450 K, at They use a supersonic jet formed of three components: combustion products, water and abrasive, and the ratio of the mass of water and abrasive is taken in the ratio of 0.2-0.3 and 1.0-1.2 of the mass of combustion products, respectively.

Moreover, in the particular case of using the method, a supersonic jet is directed to the surface to be treated at an angle of 60 ° -80 ° and from a distance equal to 15-25 critical diameters of the supersonic nozzle, and surface treatment is carried out at a speed of 0.5-0.7 m / s the movement diagram shown in Fig.1.

A thermoabrasive treatment machine comprising a compressor, vessels for fuel and an abrasive connected to each other, and an accelerator with a combustion chamber with fuel nozzles, a bottom, an abrasive nozzle in the form of a barrel and a casing in which a supersonic nozzle is placed, and according to the invention it is equipped with a vessel under water, connected by pipelines to the compressor, and vessels for fuel and abrasive, an ejector located in the accelerator, an additional combustion chamber with tangential openings at the bottom, installed with a thermal gap ohm, placed from the condition of ensuring the extension of the combustion chamber, and coaxially to the combustion chamber, installed in the bottom of the fuel pipe, a thermoprotective sheath and a stabilizer are fixed outside, the latter is connected to the fuel pipe by jet nozzles and ultrasonic dispersers, made in the form of glasses, placed coaxially to the jet nozzles, the combustion chamber is made with an air duct having openings for air, and which is connected to the casing, and the abrasive pipe is installed coaxially and with a clearance of sonic nozzle.

Special cases of the machine for thermoabrasive processing:

- the gap between the combustion chamber and the additional combustion chamber is made with a bore, the area of which is 2-3 times larger than the critical section of a supersonic nozzle;

- the tangential openings of the additional combustion chamber are made with through sections, the area of which is 1.5-1.9 times less than the critical section area of a supersonic nozzle;

- the supersonic nozzle is made with a shoulder, external cooling fins and air channels, the total area of which is less than 0.95-0.98 times the critical section area of a supersonic nozzle, and the length of the latter is 12-15 diameters of its critical section;

- a supersonic nozzle is installed by one half in the ejector, and the second in the air duct and with the possibility of being pressed by a shoulder to the air duct;

- it is equipped with a mixer for supplying water located at the inlet of the abrasive pipe;

- the abrasive pipe is installed from the condition of placing its output end at a distance of 1.5-2.5 diameter of the critical section of the supersonic nozzle.

Figure 1 presents a diagram of the movement of the tool "snake" and the spot heating the surface layer with short-term temperature effects of the treated surface up to 380-450 K, figure 2 - angle of attack from the nozzle exit to the treated surface, the effect of which on performance is shown in the table, figure 3 - schematically shows the machine "Beaver" (hereinafter referred to as the Machine), figure 4 - the device of the accelerator "TORCH", figure 5 - section of the fuel stabilizer, figure 6 - section of the nozzle of a supersonic, figure 7 - cross section of the ejector air distributor , in Fig.8 - graphically indicates the boundaries of the optimal mass ratio of fuel and air, in Fig.9 - the mass of water and combustion products, and in Fig.10 - abrasive and combustion products.

The machine includes an accelerator 1, vessels 2-4, respectively, for fuel, abrasive and water, connected to each other and to the compressor 5 by pipelines 6-12 with valves 13-16, while the pipelines 7 of the abrasive and 8 water are connected by a mixer 17. Accelerator 1 contains a collector 18, on which a casing 19 with a regenerative pipe 20 is mounted, in which a combustion chamber 21 with a coaxial gap 22 is located, a nozzle 23 is supersonic, an additional combustion chamber 24 with tangential openings 25 at the bottom 26. The accelerator 1 is equipped with an ejector 27, a distributor 28 s grooves 29 and a nut 30 with openings 31 radial, the combustion chamber 21 is made with an air duct 32 having openings 33 for air inlet and 34. An additional combustion chamber 24 is installed with a gap 35 thermal coaxial to the combustion chamber 21. In the bottom 26, a fuel pipe 36 is installed with a heat-shielding shell 37 outside and a barrel 38 inside. The heat-shielding shell 37 is equipped with a fuel stabilizer 39 connected to the fuel nozzle by the jet nozzles 40 and ultrasonic dispersers 41 made in the form of glasses placed coaxially with the nozzles 40. The supersonic nozzle 23 is made with a sealing shoulder 42, ribs 43 and air channels 44. It is installed by one half in the air duct 32, and the second in the ejector 27. The through section of the thermal gap 35 is two to three times larger than the critical section area of the supersonic nozzle 23. The total area of the tangential openings 25 is 1.5-1.9 times smaller than the critical section area of the supersonic nozzle 23. The diameter of the ultrasonic dispersant 41 is equal to the diameter of the tangential holes 25, and its depth is 1.5-1.8 times the diameter. The total area of the passage sections of the channels 44 of the supersonic air nozzle 23 is 0.95-0.98 times smaller than its critical section area, and the length of the supersonic nozzle 23 corresponds to 12-15 of its critical diameters. The output end 45 of the barrel 38 is placed coaxially with the supersonic nozzle 23 at a distance of 1.5-2.5 of its critical diameter, and the input end 46 is connected to the pipelines 7 of the abrasive and 8 water through a mixer 17.

The machine operates as follows. At low flow rates, fuel and air are supplied through valves 13 and 14 to the accelerator 1, mixed, and the resulting fuel mixture is ignited at the outlet of the ejector 27. Air is supplied from compressor 5 through valve 13, pipelines 9, 11, 7, and 10. In vessel 2 the pressure rises and fuel is displaced through the valve 14 and enters the accelerator 1 through the pipe 6. Reduce the fuel supply by smoothly closing the valve 13, and immediately open it, which helps to draw the flame into the additional combustion chamber 24. Increasing the valve 13 consumption of fuel components and raising the pressure in the combustion chamber 21, the accelerator 1 is brought to a stable combustion mode. A further increase in the consumption of fuel components by fully opening the valve 13 and adjusting the valve 14 allows you to set the accelerator 1 to the forced combustion mode and get the maximum amount of thermal and kinetic energy. The thermal gap 35 is reduced by lengthening the combustion chamber 21 and the additional combustion chamber 24, which leads to an increase in the amount of air supplied to the tangential openings 25, the power of the ultrasonic dispersers 41 increases, the quality of the preparation, the fuel mixture and the completeness of its combustion improve, which increases the temperature and speed a highly enthalpy supersonic jet flying out of a supersonic nozzle 23.

At the initial moment of starting up the accelerator 1, most of the air enters the thermal gap 35, and the smaller one enters the tangential openings 25, so a low speed of the fuel mixture is established in the additional combustion chamber 24, and the flame front is located near the fuel stabilizer 39, which increases reliability launch. After the accelerator 1 is brought into forced operation, the valve 15 is opened and the required amount of abrasive is supplied from the vessel 3 through the pipeline, the mixer 7 and the barrel 38. The air enters the combustion chamber 21 and participates in the combustion of the fuel. The abrasive due to aerodynamic drag is additionally accelerated by the combustion products in the supersonic nozzle 23 and further in the core of the highly enthalpy supersonic jet of combustion products, which is used as a working tool for surface treatment. During operation of the apparatus, air from the compressor 5 enters the manifold 18 through the valve 13 and the pipe 9. Then the air moves in the coaxial gap 22, through the holes 33 it enters the channels 44 between the cooling ribs 43 of the supersonic nozzle 23 and then through the holes 34 into the coaxial gap 22 and then into the combustion chamber 21 through a thermal gap 35. Fuel is supplied through pipeline 6 to the gap between the barrel 38 and the fuel pipe 36, is deployed near the output end 45 of the barrel 38 and returns to the side of the fuel stabilizer 39, cooling the protective shell 37 on its way. Then, the gaseous fuel is fed through the nozzles 40 to the ultrasonic disperser 41, where, under the influence of high-frequency oscillations, it disperses and begins to mix with air, falling into the additional combustion chamber 24 with a turbulent flow. Near the stabilizer 39, a reduced pressure zone is formed, into which the fuel mixture is returned countercurrently, which increases the stability of the combustion process, especially when starting up. In the mixer 17, water is supplied from the vessel 4 through the pipeline 8 and the valve 16. Water moistens the abrasive and together with it and air enters the combustion chamber 21 and then into the nozzle 23 supersonic. A high-enthalpy supersonic three-component jet (combustion products, abrasive and water) flies out of a supersonic nozzle, which is directed to the surface to be treated.

Empirical dependencies are established by approximating the optimal values and determining the influence of the deviation of their characteristics on the main indicators.

Thermoabrasive treatment is carried out by accelerators with small nozzles supersonic Dcr. = 7 ÷ 10 mm, medium and large Dcr. = 18 ÷ 25 mm at a pressure of 0.4 to 1.2 MPa.

Efficiency was determined by the specific consumption of abrasive per 1 m ^{2 of the} treated surface. Productivity was measured during surface treatment in the class Sa = 2.5. It was experimentally established that the best technological results can be obtained by heating the surface layer to 380-450 K (Fig.6), further heating leads to destructive processes of the processed material. A high-enthalpy supersonic three-component jet is prepared with an excess of fuel α = 0.8 ÷ 0.9 (Fig. 8), while water was supplied in a ratio of 0.2-0.3 (Fig. 9), and the abrasive was 1.0-1 , 2 masses of the dispersion medium (figure 10). At the same time, a high-enthalpy supersonic three-component jet (working tool) is directed at an angle of 60 ° -80 ° (Fig. 2) to the surface to be treated from a distance from the supersonic nozzle within 15-25 of its critical diameters.

Information sources

1. Patent RU No. 2248871, cl. B24C 1/00, 3/00, 2005.

2. UA patent No. 6318, cl. B24C 1/00, 5/00 7/00, 2005.

3. Application PCT / RU 2004/000185 (International publication WO No. 2004/01224 A1 of 11.25.2004).

4. Patent RU No. 2167756, cl. B24C 1/00, 5/00, 3/00 1999.

5. Patent RU No. 1148209, cl. ЕВВ 7/14, 1997.

6. Patent RU No. 968144, cl. ЕВВ 7/14, 1979.

7. Patent RU No. 2201329, cl. B24C 5/04, 2002.

8. Copyright certificate of the USSR, No. 967144, cl. ЕВВ 7/14, 1979.

9. Patent SU No. 1802936 A3, cl. B24C 5/04, 1991.

10. Patent SU No. 1834792 A3, cl. B24C 5/04, 1991.

11. USSR author's certificate No. 1145575, cl. B24C 5/04, 1982.

12. Patent RU No. 2163864, cl. B24C 1/00, 1997.

13. Patent RU No. 2201864, cl. B24C 7/00, 2001.

The influence of the distance (L) from the end of the barrel to the supersonic nozzle. No. p / p L: Dcr. nozzles Abrasive speed, m / s Nozzle wear,% Productivity, m ² / hour one 0.5 248 10 143 2 1,0 262 13 156 3 1,5 308 16 172 four 2.0 315 17 183 5 2,5 327 19 186 6 3.0 350 28 191 7 3,5 372 32 193

Claims (9)

1. The method of thermoabrasive processing of products, comprising treating the surface layer with a supersonic jet formed by the combustion products and abrasive supplied to the supersonic nozzle of the accelerator to destroy and remove the surface layer and heat it, characterized in that for simultaneous destruction, removal of the surface layer, its heating and increase the roughness and actual contact area, drying, degreasing, dedusting and activating the surface layer, heating the latter is carried out to 380-450 K, and use a supersonic jet formed of three components: combustion products, water and abrasive, and the ratio of the masses of water and abrasive to the mass of combustion products is taken equal to 0.2-0.3 and 1.0-1.2, respectively. 2. The method according to claim 1, characterized in that the supersonic jet is directed to the treated surface at an angle of 60-80 ° and from a distance equal to 15-25 critical diameters of the supersonic nozzle, with which the surface layer is processed at a speed of 0.5- 0.7 m / s according to the scheme of its movement, shown in figure 1. 3. Machine for thermoabrasive processing of products, comprising a compressor, vessels for fuel and abrasive, interconnected, and an accelerator with a combustion chamber with fuel nozzles, a bottom, an abrasive nozzle in the form of a barrel and a casing in which a supersonic nozzle is located, characterized in that it is equipped with a vessel for water, connected by pipelines with a compressor and vessels for fuel and abrasive, an ejector located in the accelerator, an additional combustion chamber with tangential openings at the bottom, installed with a thermal gap rum, located from the condition of ensuring the extension of the combustion chamber, and coaxially with the latter, installed in the bottom of the fuel nozzle, on the outside of which a heat-shielding shell and stabilizer are fixed, the latter is connected to the fuel nozzle by jet nozzles and ultrasonic dispersers, made in the form of cups, placed coaxially to the jet nozzles, when this combustion chamber is made with an air duct having openings for air, and which is connected to the casing, and the abrasive pipe is installed coaxially and with a clearance in excess sound nozzle. 4. The machine according to claim 3, characterized in that the gap between the combustion chamber and the additional combustion chamber is made with a bore, the area of which is 2-3 times larger than the critical section of a supersonic nozzle. 5. The machine according to claim 3, characterized in that the tangential openings of the additional combustion chamber are made with through sections, the area of which is 1.5-1.9 times less than the critical section area of a supersonic nozzle. 6. The machine according to claim 3, characterized in that the supersonic nozzle is made with a shoulder, external cooling fins and air channels, the total area of which is less than 0.95-0.98 times the critical section area of a supersonic nozzle, and the length of the latter is 12- 15 diameters of its critical section. 7. The machine according to claim 6, characterized in that the supersonic nozzle is installed by one half in the ejector, and the second in the air duct and with the possibility of being pressed by a shoulder to the air duct. 8. The machine according to claim 3, characterized in that it is equipped with a mixer for supplying water located at the inlet of the abrasive pipe. 9. The machine according to claim 3, characterized in that the abrasive pipe is installed from the condition of placing its output end at a distance of 1.5-2.5 times the diameter of the critical section of the supersonic nozzle.

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