Method of improvement of operation characteristics of turbine machine blades out of alloyed steels

FIELD: metallurgy.

SUBSTANCE: method includes polishing of the blade body by electrolyte-plasma method including part immersion in the electrolyte, formation around the treated part surface of the steam-gas enclosure, and discharge ignition between the treated part and electrolyte by means of the electric potential supply to the treated surface, at that polishing of the blade body surface is performed by two stages: initially electrical potential is applied to the treated blade (from 320 V to 350 V), and polishing is performed until minimum possible at this voltage roughness, then voltage is gradually reduced to value from 270 V to 300 V, and final polishing is performed until minimum possible at this voltage roughness, at that water solution of ammonia sulphate salt with concentration from 6 to 12 g/l is used as electrolyte, and polishing is performed at temperature from 60°C to 80°C.

EFFECT: improved operation characteristics of blades of the turbine machines upon simultaneous decreasing of treatment labour intensity.

9 cl, 1 ex

 

The invention relates to the technology of electrolytic-plasma polishing of the surface of parts made from alloy steels and can be used to improve the performance characteristics of the blades of turbomachines.

For the manufacture of blades of turbomachines used alloy steels, high strength, including high temperatures, at the same time providing a sufficiently high ductility. Blades of turbomachines of alloyed alloys have a high sensitivity to stress concentrations. Therefore, the defects generated in the manufacturing process of these parts, is invalid because that can cause intense process of destruction.

With the increase of roughness parameters the blade deteriorates the gas-dynamic stability of the engine, increase aerodynamic losses, leading to reduced efficiency, loss of power, increased unit costs and lower efficiency of the engine or installation. In addition, the surface quality of the pen blades significantly affects their strength characteristics, for example, improving the cleanliness of the surface increases the limit of endurance and static strength of blades (V. F. Makarov, E. N. Bull, A. O. Chuyan. Mathematical modeling of the process of polishing the blades of gas turbine �of motors // aerospace technique and technology. No. 8 (85), 2011, pp. 11-14).

At the same time, the production and repair of blades of gas turbine engines and motors, due to the high quality requirements of the surface (Ra≤0,32...to 0.16 μm), is characterized by considerable complexity of their finishing. This causes problems when machining surfaces of parts of turbomachines. In this regard, the development of methods of obtaining high-quality surfaces of parts of turbomachines is very important task.

A method of polishing the blades airfoil GTE radar range at which the blade reported reciprocating movement relative to the tool (as the USSR №1732604. IPC B24B 19/14. METHOD of POLISHING the PEN of GTE BLADES PETAL CIRCLE), in which the polishing is made with the petal deformation of the circle.

There is also known a method of processing, allowing for polishing a curved edge of the pen blades of a gas turbine fueled by the radius of the polishing wheel moving along the blade (Patent RF №2379170. IPC B24B 19/14. A METHOD OF PROCESSING BLADES OF GAS TURBINE ENGINES. 2010).

However, the application in the known methods of polishing the surface of the pen blades mechanical stress on the workpiece causes the deterioration of the quality parameters of the surface layer of materials, which leads to lower operational characteristics�IR blades, especially having a small thickness of the pen.

The most promising methods of processing blades of turbomachines are electrochemical methods of polishing surfaces [Griliches, SJ Electrochemical and chemical polishing: Theory and practice. The influence on the properties of metals. L., mechanical engineering, 1987], with the greatest interest to this field are the methods of electrolytic-plasma polishing (EPP) parts [for example, Patent GDR (DD) No. 238074 (A1), IPC C25F 3/16, publ. 06.08.1986 and Patent of the Republic of Belarus No. 1132, IPC C25F 3/16, 1996, BI No. 3].

A method of polishing metal surfaces, including anodic treatment in an electrolyte [Patent of RB №1132, IPC C25F 3/16, 1996, BI No. 3] and the method of electrochemical polishing [U.S. Patent No. 5028304, IPC B23H 3/08, C25F 3/16, C25F 5/00, publ. 02.07.1991].

Known methods of electrochemical polishing is not allow to produce high-quality polishing of the surfaces of alloy steels.

Closest to the claimed technical solution is a method of electrolytic-plasma polishing of the details of the alloys comprising immersing the workpiece in the electrolyte, the formation around the workpiece part steam-gas shell and the ignition of the discharge between the workpiece and the electrolyte by feeding on the workpiece of the electric potential [PA�UNT of the Russian Federation No. 2373306, IPC C25F 3/16. Bulletin No. 32, 2009].

However, the known method [RF Patent №2373306], provides for the machining of titanium alloys and can be applied to machining of the blades of alloy steels.

The problem to be solved by the claimed invention is to improve such performance characteristics of the blades of turbomachines of alloy steels, in fatigue and static strength, accompanied by a decrease in the roughness of the surface of the pen blades, as well as enhancing the functional properties of the blades, providing a higher efficiency of the plant.

The technical result of the invention is to increase the performance of the blades of turbomachines of alloyed steels and improvement of their functional properties by improving the quality of the processing surface of the blade while reducing the complexity of the treatment process.

The technical result is achieved in that in the method of improving performance characteristics of the blades of turbomachines of alloyed steel, comprising polishing the surface of the blade in contrast to the prior art, polishing the blade carry out electrolytic-plasma method comprising immersing the workpiece in the electrolyte, the formation around the workpiece part steam-gas shell and the ignition of the discharge m�waiting for the workpiece and the electrolyte by feeding on the workpiece of the electric potential, and polishing the surface of the blade is produced in two stages: first, to treat shoulder blade applied electric potential value between 320 and 350 In and carry out polishing until achieving the minimum possible for a given voltage values of roughness, and then gradually reduce the voltage to values from 270 to 300 and will conduct a final polishing to achieve the minimum possible for a given voltage magnitude of surface roughness, wherein the electrolyte is an aqueous salt solution of ammonium sulfate concentration from 6 to 12 g/liter, and the polishing is conducted at a temperature from 60°C to 80°C, two possible options for the implementation of the method: polishing the blade is operated at a current of 0.2 A/DM2to 0.8 A/DM2as the blades of turbomachines using a compressor blade of a gas turbine engine, the blades of turbomachines using a compressor blade of a gas turbine installation; as the blades of turbomachines use the paddle pumping plants; the composition of the electrolyte is further added surfactant concentration, weight. per cent from 0.6 to 1.2.

The claimed method of electrolytic-plasma polishing of the surface of the pen blades in the process of its manufacture or reconditioning is carried out as about�time. The process of electrolytic-plasma polishing is carried out in two stages: first, to treat shoulder blade applied electric potential value between 320 and 350 In and carry out polishing until achieving the minimum possible for a given voltage values of roughness, then slowly reduce the voltage to values from 270 to 300 and will conduct a final polishing to achieve the minimum possible for a given voltage magnitude of surface roughness. The electrolyte is an aqueous salt solution of ammonium sulfate concentration from 6 to 12 g/liter, and the polishing is conducted at a temperature from 60°C to 80°C to obtain the desired surface roughness. Polishing the pen, depending on the settings part of the processing area of 1 cm2to 4000 cm2and given microgeometry of the surface is carried out at a current of 0.2 A/DM2to 0.8 A/DM2. To improve the quality of the processing, the composition of the electrolyte may be added a surfactant in a concentration of, by weight %: from 0.6 to 1.2%. Buffing the surface of the pen blades are in the environment of the electrolyte while maintaining around the details of the steam-gas shell. As the bathtubs use container, made of a material resistant to the electrolyte.

In the method the following processes occur.Under the action of flowing currents heats the surface of the part and the formation around it of a combined cycle shell. Excessive heat caused during the heating of the workpiece and the electrolyte is discharged through the cooling system. Thus maintain the desired process temperature. Under the action of electric voltage (electric potential between the workpiece and the electrolyte) in combined cycle shell there is a discharge of electrolytic ionized plasma, providing a course of intensive chemical and electrochemical reactions between the workpiece and the vapor-gas environment of the shell.

When applying a positive potential to the detail, during the course of these reactions occurs anodizing the surface of the part is simultaneously formed by chemical etching of oxide. Moreover, the anodic polarization of the gas-vapor layer consists of a vapor of the electrolyte anions and gaseous oxygen. Since the etching occurs mainly on the finish, where a thin oxide layer, and anodizing processes continue, the result of joint action of these factors is the removal of the coating from the machined surfaces of the parts. The surfactant reduces the surface tension of the solution that improves the condition of the vapor-gas layer at the border "gas-liquid". But there should be no significant concentrations of surfactants, because this can lead � the formation of undesirable indelible films on the surface of the product. In addition, increasing the concentration of surfactant can lead to the opposite effect, i.e. to increase the value of surface tension of the solution. To minimize Joule of lescovich losses, the electrolyte must have sufficient conductivity.

Example. Processed samples blades of alloyed steel was immersed in a bath of an aqueous electrolyte solution and applied to the workpiece is positive, and to the electrolyte - negative voltage. Buffing the surface of the pen blades made in two stages: first, to treat shoulder blade applied electric potential value between 320 and 350 In and spent polishing to achieve the minimum possible for a given voltage values of roughness, then gradually reduced the voltage to values from 270 to 300 and spent the final polishing to achieve the minimum possible for a given voltage magnitude of surface roughness. Polishing was performed in the environment of the electrolyte: aqueous salt solution of ammonium sulfate concentration from 6 to 12 g/liter. In addition, in some cases, the composition of the electrolyte additionally injected additives surfactants at a concentration of 0.6-1.2%. When processing was performed circulation cooling of the electrolyte was maintained at the average process temperature in the range of 60°...80°C).

Processing conditions �of the proposed method: electric potential (voltage), first stage: from 320 to 350 (300 - Unsatisfactory result (N. R.); 320 In - Satisfactory result (U. R.); 320 In - U. R.; 340 In - U. R.; 350 - U. R.; 370 - N. R.); first stage: (250 In - (N. R.); 270 - (W. R.); 280 In - U. R.; 290 In - U. R.; 300 V - U. R.; 320 - N. P.). The electrolyte is an aqueous salt solution of ammonium sulfate concentration (4 g/liter - N. R.; 6 g/liter, W. R.; 10 g/liter, W. R.; 12 g/liter, W. R.; 14 g/l - N. R.; additives in the electrolyte-surfactant in a concentration of: (a 0.4% N. R.; 0.6% Of U. R.; 0,8% - U. R.; 1,2% - U. R.; 1,4% - N. R.); the magnitude of the current from 0.2 A/DM2to 0.8 A/DM2at a temperature of from 70°C to 90°C (60°C - N. R.; 70°C U. R.; 80°C, U. R.; 90°C U. R.; 98°C - N. R.).

Compared to used mechanically polishing (Patent RF №2379170) the performance of the process according to the proposed method, on average, 3-4 times, and average values of surface roughness Ra of 0.65 0.45 µm..., for the proposed method is improved to Ra 0.03 to 0.02 µm....

The use of the method of improving performance characteristics of the blades of turbomachines of alloyed steel, comprising the following features: polishing the surface of the pen blades plasma electrolytic method; comprising: immersing a workpiece in the electrolyte; the formation around the workpiece part steam-gas shell; an ignition discharge between the workpiece and the electrolyte by feeding on the workpiece elect�with on-demand capacity; polishing the surface of the blade is produced in two stages: first, to treat shoulder blade applied electric potential value between 320 and 350 In and carry out polishing until achieving the minimum possible for a given voltage values of roughness, and then gradually reduce the voltage to values from 270 to 300 and will conduct a final polishing to achieve the minimum possible for a given voltage magnitude of surface roughness; the electrolyte is an aqueous salt solution of ammonium sulfate concentration from 6 to 12 g/liter; the polishing is carried out at a temperature from 60°C to 80°C; polishing the blade is operated at a current of 0.2 A/DM2to 0.8 A/DM2as the blades of turbomachines using a compressor blade of a gas turbine engine, the blades of turbomachines using a compressor blade of a gas turbine installation; as the blades of turbomachines use the paddle pumping plants; the composition of the electrolyte is further added surfactant concentration, wt %: from 0.6 to 1.2 help you to achieve the present invention the technical result is to increase the performance of the blades of turbomachines of alloyed steels and improvement of their functional properties by improving the quality of treatment�tki surface of the blade while reducing the complexity of the treatment process.

1. A method of processing blades of turbomachines of alloyed steel, comprising polishing the surface of the blade, characterized in that the polishing of the blade is carried out electrolytic-plasma method comprising immersing the workpiece in the electrolyte, the formation around the workpiece part steam-gas shell and the ignition of the discharge between the workpiece and the electrolyte by feeding on the workpiece of the electric potential, and polishing the surface of the blade is produced in two stages - initially processed to make the blade the electric potential value between 320 and 350 In and carry out polishing until achieving the minimum possible for a given voltage values of roughness, and then gradually reduce the voltage to values from 270 to 300 and will conduct a final polishing to achieve the minimum possible for a given voltage magnitude of surface roughness, wherein the electrolyte is an aqueous salt solution of ammonium sulfate concentration from 6 to 12 g/liter, and the polishing is conducted at a temperature from 60°C to 80°C.

2. A method according to claim 1, characterized in that the polishing of the blade is operated at a current of 0.2 A/DM2to 0.8 A/DM2.

3. A method according to claim 1, characterized in that the blades of turbomachines use the paddle comp�of essor gas turbine engine.

4. A method according to claim 2, characterized in that the blades of turbomachines using a compressor blade of a gas turbine engine.

5. A method according to claim 1, characterized in that the blades of turbomachines using a compressor blade of a gas turbine installation.

6. A method according to claim 2, characterized in that the blades of turbomachines using a compressor blade of a gas turbine installation.

7. A method according to claim 1, characterized in that the blades of turbomachines using a shovel gas compressor installation.

8. A method according to claim 2, characterized in that the blades of turbomachines using a shovel gas compressor installation.

9. A method according to any one of claims.1-8, characterized in that the composition of the electrolyte is further added surfactant concentration, wt.%: from 0.6 to 1.2.



 

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