RU2378420C2 - Installation for electrolytic-plasma treatment - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: invention can be used in turbomachinery at polishing of blades. Installation contains at least one operating cell with electrolyte, device for fixation of treated products and power supply for electrolytic - plasma treatment, herewith in operating cell in treatment area of products there are located inducers, outfitted by at least one power supply for induction heating of parts.

EFFECT: providing ability of selection of optimal operating modes, increasing of process flexibility and reduction of operating potentials.

6 cl, 1 dwg, 1 tbl, 1 ex

Description

The invention relates to the field of electrochemical processing of parts, in particular to installations for electrolyte-plasma polishing of metal products, mainly from chromium-containing stainless steels, alloys, as well as titanium and titanium alloys, and can be used in turbomachinery when processing working and guide vanes of steam turbines, vanes gas pumping units and compressors of gas turbine engines, in order to ensure the necessary physical, mechanical and operational properties of parts of the tour bomash, as well as a preparatory operation before the ion-implantation modification of the surface of the part and the application of protective ion-plasma coatings.

The working blades of the compressor of a gas turbine engine (GTE) and gas turbine installation (GTU), as well as steam turbines during operation, are exposed to significant dynamic and static loads, as well as corrosion and erosion destruction. Based on the performance requirements for the manufacture of gas turbine compressor blades, high-alloy chromium, chromomolybdenum (CrMo), chromomolybdenum-vanadium (CrMoV) and other medium and high alloy steels are used (for example, for steam turbine blades - steel grades 20X13 and 15X11MF, gas - steel 20X13, HEY 961). These steels are among stainless steels with a Cr content of 11-14%, differing in the content of alloying elements: C, Mo, V. In addition, titanium alloys are used for the manufacture of gas turbine compressor blades, which are higher in comparison with technical titanium strength, including at high temperatures, while maintaining a sufficiently high ductility and corrosion resistance (for example, titanium alloys of the grades VT6, VT14, VT3-1, VT22, etc.).

However, turbine blades of these steels and alloys are highly sensitive to stress concentrators. Therefore, defects formed in the manufacturing process of these parts are unacceptable, since they cause the occurrence of intense destruction processes. This causes problems when machining surfaces of turbomachine parts. In this regard, the development of methods for producing high-quality surfaces of turbomachine parts is a very urgent task.

The most promising methods for processing turbomachine blades are electrochemical methods of polishing surfaces [Griliches S.Ya. Electrochemical and chemical polishing: Theory and practice. Effect on the properties of metals. L .: Engineering, 1987], while the most interesting for the area are electrolyte-plasma polishing (EPP) parts [for example, patent GDR (DD) No. 238074 (A1), class. C25F 3/16, publ. 08/06/86., As well as the patent of the Republic of Belarus No. 1132, class. C25F 3/16, 1996, BI No. 3].

A device is known (USSR AS No. 1039251, IPC С25F 7/00, 04.01.81) containing a bath for an electrolyte, a working electrode and an electrolyte circulation system, including a centrifugal pump with a nozzle for supplying electrolyte, a window with a nozzle for returning the electrolyte.

There is also known a device for processing in electrolyte plasma (RF patent No. 20099212, IPC C21D 1/44, 03.15.94) containing a bath with electrolyte and a test electrode placed in it, a power source, the device is equipped with a ferromagnetic device that can move relative to the test electrode a rod magnetically closed with a test electrode through a magnetic circuit with two inductors, and a power supply unit electrically connected to one of the coils, and the other coil is electrically connected to the power source through a recording device and a reverse ide.

The closest in technical essence is the electrolyte-plasma polishing unit selected as a prototype (RF patent No. 2268326, IPC С21D 1/44, 03.15.94), containing pneumatic cylinders, a suspension with cartridges, two working baths, an electrolyte correction bath, a pump for pumping solution, column, clamps for fixing products, a pre-loading chamber, a diffusion filter for pumping a solution, characterized in that an electric heater, a heat exchanger and a level sensor are introduced into the electrolyte correction bath, and the body of the working bath is etsya cathode.

The main disadvantages of the known devices include the complexity, and in some cases the inability to ensure a reliable processing mode during the start of the process, as well as stabilization by temperature. As a result of this, the likelihood of defects significantly increases. These defects that have arisen on the surface of the part are inherited during further processing, which leads to significant uneven processing of the part, thereby deteriorating its quality. This, in particular, is due to the fact that, during the period of entering the processing mode, fluctuations in the magnitude of the input electric power cause strong changes in the temperature regime on the surface of the part, which makes the process extremely unstable and increases the likelihood of defects, especially for the polishing process.

The task to which the invention is directed is to enable the selection of optimal processing conditions and increase the flexibility of the process due to the possibility of separate creation and control of the parameters of the gas-vapor envelope and plasma discharge in it, as well as lowering the values of the working potentials between the part and the electrolyte required process and processing.

The technical result is achieved by the fact that in the installation of electrolyte-plasma treatment containing at least one working bath with electrolyte, a device for attaching workpieces and a power source for electrolytic-plasma processing, in contrast to the prototype in the working bath, are located in the processing zone of the products Inductors equipped with at least one power source for induction heating of parts.

The technical result is also achieved by the fact that the installation further comprises a pump for pumping the electrolyte and an electrolyte correction bath equipped with a heat exchanger, wherein the working baths and the correction bath are configured to combine their volumes and create a common electrolyte circulation system; in addition, in addition, a level sensor may be introduced into the electrolyte correction bath.

The technical result is also achieved by the fact that the installation may further comprise a dispersion filter for pumping the solution, as well as a pre-loading chamber and a device for loading and removing parts from the electrolyte.

The technical result is also achieved by the fact that the installation can additionally contain inductors made with the possibility of placing workpieces in their cavities, the working bath is a cathode, and the installation has a control unit for stabilization and automation of the process.

The invention is illustrated by drawings. Figure 1 shows the layout of the proposed installation.

The plasma-electrolyte treatment installation comprises a working bath 1, an electrolyte correction bath 2, an electrolyte pump 3, a cassette 4 with clamps 5 for workpieces 6. The working bath has a lid 7 with windows for cartridges 4. A device 8 is installed in the working bath 1 for electrolyte supply and inductors 9 for heating the surface of the parts. The electrolyte correction bath 2 is equipped with a heat exchanger 10 and a level sensor 11. The installation is equipped with two power sources: a power source for conducting the electrolyte-plasma treatment process and a power source for induction heating, as well as a processing process control unit with a control panel. As baths 1 and 2 use containers made of a material resistant to electrolyte.

Installation of electrolyte-plasma processing works as follows. The workpieces 6 are installed in cassettes 4, fixed with clamps 5 and lowered into the working bath 1. After that, the parts are processed according to one of the following schemes:

- processing according to the scheme: "preliminary induction heating of the part and the formation of a gas-vapor shell (PGO) - ignition of the plasma decomposition in the formed PGO - access to the processing mode with a gradual decrease in the proportion of induction heating of the part - the processing process without induction heating";

- processing according to the scheme: “preliminary induction heating of the part and the formation of PGO — ignition of a plasma discharge in the formed PGO — exit to the processing mode with a gradual transition of the induction heating of the part in the support mode”;

- processing according to the scheme: “simultaneous induction heating of the part and supply of potential to the part both at the start of the process and during its implementation”;

- processing according to the scheme: “induction heating of a part by high-frequency currents (HDTV), the formation of HDTV plasma and processing only HDTV (without supplying potential to the part (from a power source)”;

- processing according to the scheme: “induction heating of a part by high-frequency currents (HDTV), the formation of high-frequency plasma and processing together with high-frequency plasma when combined with the supply (positive or negative) of the potential to the part from the power source;

- processing according to the scheme: "supplying potential to the part - the formation of PGO and ignition of a discharge in it" (similar to the prototype installation).

When using the above processing schemes, depending on the objectives, conditions and conditions are created that allow either: electrolyte-plasma polishing of parts, or - obtaining coatings, or - hardening of parts, or their chemical-thermal treatment.

When processing on the proposed installation according to the scheme:

“Preliminary induction heating of the part and the formation of a gas-vapor shell (PGO) - ignition of a plasma discharge in the formed PGO - access to the processing mode with a gradual decrease in the fraction of induction heating of the part — the implementation of the processing process without induction heating”, perform the following actions. The metal part 6 to be treated is immersed in a bath 1 with an aqueous solution of electrolyte, placed in the cavity of the inductor 6, induction heating of the part 6 until a vapor-gas shell is formed around the part, a positive voltage is applied to the part 6, and a negative voltage is applied to the electrolyte (anodic treatment) or applied to details 6 negative voltage, and to the electrolyte - positive (cathodic treatment), due to which ignite the plasma discharge between the workpiece and the electrolyte. Then, a transition to the processing mode is carried out with a gradual decrease in the fraction of induction heating of the part until it is completely turned off and the electrolyte-plasma processing process is carried out only by supplying potential to the part. Processing is carried out in an electrolyte medium while maintaining a vapor-gas shell around a part.

When carrying out electrolyte-plasma treatment using induction heating, the following processes occur. Under the influence of induction currents, the surface of the part is heated and a vapor-gas shell forms around it. Excessive heat arising from the induction heating of the part and, in part, of the electrolyte is removed through the cooling system, while maintaining the desired process temperature. Under the action of electric voltage (electric potential between the part and the electrolyte), a discharge arises in the vapor-gas shell, which is an ionized electrolytic plasma, which ensures the flow of intensive chemical and electrochemical reactions between the treated part and the medium of the gas-vapor shell.

When a positive potential is applied to a part during the course of these reactions, the surface of the part is anodized with simultaneous chemical etching of the formed oxide. Moreover, with anodic polarization, the vapor-gas layer consists of electrolyte vapors, anions, and gaseous oxygen. Since etching occurs mainly on microroughnesses, where a thin oxide layer is formed, and the anodizing processes continue, as a result of the combined action of these factors, the roughness of the treated surface decreases and, as a result, polishing of the latter occurs.

In the case of cathodic polarization, the vapor-gas shell around the part consists of electrolyte vapors, cations and hydrogen gas, therefore, along with the chemical interaction of cations with the material of the surface layer of the part, micro spark discharges occur in the vapor-gas shell, which leads to electroerosive and cavitation effects on the treated surface.

The process of electrolyte-plasma polishing on the proposed installation is as follows. After installation and fixing in the clamps 5 of the cartridge 4 of the workpiece 6 they are lowered into the working bath 1. The cartridge 4 is connected to the positive pole of the power source. Cassettes 4 are arranged so that the parts 6 are placed in the cavity of the inductors 9 (for protection against direct contact of the parts 6 from the inductor 9, guides are made in the form of a truncated inverted cone without bottoms). The negative pole of the power source is connected to the contacts located directly on the outer side of the wall of the working bath 1.

The electrolyte is supplied through the device 8. During the installation, the electrolyte circulates in the total volume of baths 1 and 2. In the bath 2, the chemical composition of the solution is corrected by introducing components, as well as to maintain a given temperature range of the solution. To maintain the working level of the electrolyte in the bath 2, a sensor 11 is provided. The pump for pumping the solution directs the electrolyte from the correction bath 2 to the working bath 1. For the convenience of processing parts and increasing productivity, two, three or four working baths can be used. The control unit and control panel are designed to set and maintain the specified parameters of the part processing process.

Example. Two batches of samples in the form of metal plates made of stainless steel 12X18P10T with dimensions of 50 × 20 × 2 mm with an initial roughness of R _a = 0.12 μm, were processed in two ways - according to the proposed and prototype.

According to the proposed option, the samples were immersed in a bath with an aqueous electrolyte solution and placed in the inductor cavity, induction heating was performed until a vapor-gas shell was formed around the part, then a positive voltage was applied to the plates, and a negative voltage was applied to the plates. Parts were machined in an electrolyte based on an aqueous solution of sodium hydrogencarbonate salt. The electrolyte was circulated cooled (the average process temperature was maintained at 45-60 ° C). In the prototype embodiment, similar process conditions were used, with the exception of induction heating of the samples.

The table shows the test results of samples made of stainless chromium-nickel steel.

Option No. No. p / p According to the prototype According to the proposed method Concentration solution, wt.% Potential difference, V Microroughness height after processing, R _a , microns Application Concentration solution, wt.% Potential difference, V Microroughness height after processing, R _a , microns Application one 2 3 four 5 6 7 8 9 10 one one 5 twenty - The vapor-gas shell did not form 5 twenty 0.12 (-) 2 10 twenty - 10 twenty 0.11 (+) 3 fifteen twenty - fifteen twenty 0.12 (-) four twenty twenty - twenty twenty 0.11 (+) 2 5 5 thirty - The vapor-gas shell did not form 5 thirty 0.05 (+) 6 10 thirty - 10 thirty 0.05 (+) 7 fifteen thirty - fifteen thirty 0,03 (+) 8 twenty thirty - twenty thirty 0,03 (+) 3 9 5 one hundred - Process unstable 5 one hundred 0,03 (+) 10 10 one hundred - 10 one hundred 0.02 (+) eleven fifteen one hundred - fifteen one hundred 0.02 (+) 12 twenty one hundred - twenty one hundred 0.02 (+) four 13 5 200 0.08 (+) 5 200 0.02 (+) fourteen 10 200 0.08 (+) 10 200 0,03 (+) fifteen fifteen 200 0.06 (+) fifteen 200 0,03 (+) 16 twenty 200 0.06 (+) twenty 200 0.02 (+) 5 17 5 300 0.06 (+) 5 300 0,03 (+) eighteen 10 300 0.08 (+) 10 300 0.02 (+) 19 fifteen 300 0.06 (+) fifteen 300 0,03 (+) twenty twenty 300 0.04 (+) twenty 300 0.04 (+) one 2 3 four 5 6 7 8 9 10 6 21 5 400 0.06 (+) 5 400 0.04 (+) 22 10 400 0.06 (+) 10 400 0.04 (+) 23 fifteen 400 0.08 (+) fifteen 400 0.06 (+) 24 twenty 400 0.06 (+) twenty 400 0.06 (+) 7 25 5 500 - Microprotrusion reflow 5 500 - Microprotrusion reflow 26 10 500 - 10 500 - 27 fifteen 500 - fifteen 500 - 28 twenty 500 - twenty 500 -

The proposed installation, unlike the prototype, provides the ability to select the optimal processing conditions and allows to increase the flexibility of the process due to the possibility of separate creation and control of the parameters of the gas-vapor envelope and plasma discharge in it, as well as lowering the values of the working potentials between the part and the electrolyte necessary to start the process and conducting processing. Due to this, the proposed installation can improve the quality of surface treatment of parts.

Claims (6)

1. Installation of electrolyte-plasma treatment, containing at least one working bath with electrolyte, a device for attaching workpieces and a power source for electrolyte-plasma processing, characterized in that in the working bath in the processing zone of the products are inductors equipped with at least one power source for induction heating of parts. 2. Installation according to claim 1, characterized in that it further comprises an electrolyte pump and an electrolyte correction bath equipped with a heat exchanger, wherein the working baths and the correction bath are configured to combine their volumes and create a common electrolyte circulation system. 3. Installation according to claim 2, characterized in that it further comprises a level sensor located in the electrolyte correction bath. 4. Installation according to claim 3, characterized in that it further comprises a dispersion filter for pumping the solution. 5. Installation according to claim 4, characterized in that it further comprises a pre-loading chamber and a device for loading and removing parts from the electrolyte. 6. Installation according to any one of claims 1 to 5, characterized in that the inductors are arranged to accommodate workpieces in their cavities, the working bath is a cathode, and the installation is additionally equipped with a control unit for stabilization and automation of the process.

Images