RU2389927C1 - Procedure for fabricating brush packing - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: procedure for fabricating brush packing of circular slit in form of circular case or case in form of set of circular segments and solid insertion or set of solid insertions corresponding to base with multitude packing element arranged thereon consists in forming multitude of packing elements on treated surface of each metal work-piece of insertion by method of pulse electro-chemical treatment with electrode-tool. The brush packing corresponds to a perforated plate successively bent. Each solid insertion is attached in bent position to the circular case or circular segments, further interconnected.

EFFECT: invention eliminates overflow of gas through circular slit between rotating and fixed components of compressors and turbines.

4 cl, 8 dwg

Description

The invention relates to the manufacturing technology of ring brush sealing products designed to eliminate gas flow through the annular gap between the rotating and stationary parts of compressors and turbines, mainly for gas turbine engines and steam turbines.

A known method of manufacturing a brush seal, in which layers of tightly fitting metal wires are formed into a package with the layers being positioned using gaskets, the package is fixed with compression using the side plates of the seal, the working and opposite ends of the package are cut and the package is welded to the gaskets and plates according to the latter [Patent RF 2076256, F16J 15/00, publ. 03/27/1997].

The disadvantage of this method of manufacturing a brush seal is the complexity of the organization and automation of its production in mass production. In addition, after trimming the working ends of the package, a non-cylindrical surface of the brush is formed, which leads to the need for its refinement by grinding or EDM [Zrelov V.V., Krashennikov K.P. Technology of brush seals // Improving the technology of manufacturing parts in the aircraft industry. Samara, 1996. S. 65-74]. The use of packaging welding leads to the appearance of thermally weakened layers, which can cause destruction of the bristles in the weld areas and their subsequent loss from the packaging during operation (especially under severe operating conditions - high temperatures and high peripheral speeds).

A known method of manufacturing a brush seal, including the manufacture of the brush base, installing brush wires on it and securing them between the side plates of the housing, in which the brush blank is cut off, the base with the wires are zigzag around, leaving the bends of the base free from wires. The resulting flat brush is rolled into a ring, after which the bends of the base on one side are displaced in the circumferential direction relative to the bends of the base on the other side and the brush is clamped at the places of the bends between the side plates of the housing [A. USSR No. 1462916, F16J 15/16, publ. 1989].

The disadvantage of this method, as well as the previous one, is the difficulty of its implementation in conditions of high-performance automated production.

A known method of manufacturing a brush seal, including applying a fixing composition to the wire during winding throughout the thickness of the sealing bag, welding the seal and drying it, followed by mechanical removal of the sealing and fixing composition on the outer open annular portion of the seal [A.S. USSR No. 1484033, F16J 15/16, publ. 2005].

The disadvantage of this method is the high complexity of its implementation and automation. The disadvantages include the need for additional refinement of the open (working) annular portion of the brush and reduced reliability of the seal due to the use of the welding operation.

None of the known methods makes it possible to produce a brush seal with various in cross and longitudinal section forms of bristles (hereinafter referred to as sealing elements), which is necessary to ensure special sealing and mechanical properties (flexibility, strength, etc.). Also, none of the known methods does not provide high definition location of the sealing elements in the array and the stability of the gaps between them.

These shortcomings can be eliminated by using the technology of pulsed electrochemical processing, which allows you to form protrusions of various shapes on the flat surface of a metal billet [Zaitsev AN, Agafonov I.L., Amirkhanova N.A. et al. Precision electrochemical processing by pulsed current / Ufa: Gilem, 2003. - 196 p., s.159]. However, the use of this method for the manufacture of brush seals is not known.

The objective of the invention is the manufacture of brush seals with different longitudinal and transverse shapes of the sealing elements and their clear relative position; increasing the automation of seal manufacturing technology; increased reliability of the seal.

The problem is solved by a method of manufacturing a brush seal of an annular gap in the form of an annular housing or a housing in the form of a set of annular segments and a monolithic insert or a set of monolithic inserts, which are a base with a plurality of sealing elements located on them, consisting in the formation of each method by pulsed electrochemical processing on the treated surface a metal preform for inserting a plurality of sealing elements using an electrode tool representing a perforated plate, followed by bending and fixing each monolithic insert in a curved position in the annular body or ring segments, which are subsequently connected to each other.

In addition, a wear-resistant coating with a thickness of 10 ... 20 μm more than is required to be obtained at the working ends of the sealing elements is applied to the treated surface of the insert blank before electrochemical treatment.

In addition, before electrochemical treatment, hardening and at least one aging of the insert blank is carried out.

In addition, after electrochemical treatment, the insert is filled with a sealing compound to a part of the height of the sealing elements.

The invention is illustrated by the drawings and photographs. Figure 1 shows a sketch of the design of the brush seal for manufacturing by the proposed method, figure 2 is a section aa in figure 1. Figure 3 shows the technological scheme for the formation of sealing elements of circular cross section on the machined surface of the metal billet of the insert by pulse electrochemical processing (ECHO). Figure 4 schematically shows an insert after a pulsed ECHO, figure 5 schematically shows an insert after bending with a radius R. Figure 6 is a process diagram of a pulsed ECHO of inclined circular sealing elements. 7 shows a full-scale sample insert brush insert with sealing elements of circular cross section, obtained by the method of pulsed ECHO; on Fig - full-scale sample of the insert assembly with an annular segment obtained by the proposed method.

The proposed method can find application in the manufacture of a brush seal designed to eliminate the flow of gas (steam, oil) through an annular gap separating the cavities of high and low pressure, and containing many sealing elements 1 (Fig. 1), between which there are gaps 2 (Fig. .2). The seal itself is made in the form of a set of inserts 3, each of which is a thin flexible base 4, made in one piece with many sealing elements 1. The inserts 3 are securely fixed in a curved position in the housing 5, made in the form of a ring or a set of ring segments. The brush seal may have sealing elements located radially or at an angle to the radius of the annular gap in the radial or axial plane.

The technological scheme of the electrochemical formation of many sealing elements located on a thin base, is as follows.

The conductive densely perforated plate 6 (figure 3) is connected to the negative pole of the power source 7 and is an electrode-tool (EI). It performs, together with the housing 8 of the electrode holder, a feed movement V _EI in the direction of the workpiece surface of the insert 9 and a reciprocating vibrational motion with a frequency f _EI . The blank of the insert 9 is connected to the positive pole of the power source 7 and is an anode. In the process of processing through the hole 10 in the housing 8 of the electrode holder under pressure R _EL supplied electrolyte. The electrolyte flow is partially stabilized in the upper cavity 11 of the housing 8 and, passing through the leveling grid 12, enters the lower cavity 13 and then into the interelectrode gap between the densely perforated plate 6 and the workpiece of the insert 9. The inner part of the electrode holder body 8 is insulated (for example, coated with a non-conductive composition )

The shape of the holes in the electrode-tool is determined based on the required shape of the sealing elements, and the dimensions are adjusted for the lateral interelectrode gap s _b (Fig.3).

The pulsed electrochemical treatment is carried out until the insert base thickness is 0.3 ... 5 mm, depending on the radius of the annular gap being sealed. For example, from our practice it is known that to obtain an annular brush seal of radius R = 200 mm, the thickness of the base of the insert should be c = 0.5 ... 1 mm (figure 4).

After conducting a pulse ECHO, the insert is bent so that the cylindrical surface tangent to the working ends of the sealing elements has a radius equal to the radius of the annular gap being sealed (Fig. 5) and is securely fixed (inserted with an interference fit, pressed in, clamped with fasteners, soldered, etc.). n.) in an annular housing or an annular segment. If the housing is a set of annular segments, then further connect the annular segments with inserts with each other.

When the electrochemical formation of sealing elements located at an acute angle φ to the surface of the insert blank (Fig. 6), the shape of each sealing element in a section perpendicular to its axis is distorted (compressed) in the direction of its inclination in proportion to the shape of the hole in the electrode-tool in proportion the sine value of this angle. Therefore, to obtain sealing elements of the required shape and size, an electrode tool with holes is used, the shape of which is elongated in the direction of inclination of the sealing elements in proportion to the cosecant of the angle of inclination, taking into account the magnitude of the lateral interelectrode gap. For example, to obtain round sealing elements of diameter d in the cross section, the holes in the densely perforated plate must be in the form of an ellipse with half shafts a = (0.5d + s _b ) and b = (0.5d + s _b ) / sinφ = (0 , 5d + s _b ) × cscφ.

The friction of the sealing elements on the surface of the rotor part (shaft, blades) during operation leads to their rapid wear. Therefore, to increase the life of the brush seal, the working ends of the sealing elements must have a wear-resistant coating. It is applied to the machined surface of the insert blank before the start of the pulsed ECHO process itself. Since at the beginning of the pulsed ECHO process (when the electrode-tool is inserted into the workpiece), the insert is dissolved over the entire processed surface of the insert, this leads to the fact that a small layer of metal (about 10 ... 20 μm thick) is removed from the processed surface of the insert blank holes in the electrode-tool, as a result of which on the working ends of the sealing elements, the wear-resistant coating has a smaller thickness than on the surface of the insert workpiece before a pulse ECM. In this regard, the thickness of the wear-resistant coating applied to the treated surface of the insert blank should be 10 ... 20 microns more than what is required to be obtained at the working ends of the sealing elements.

To increase the strength and improve the elastic (damping) properties of the sealing elements, the insert blank is subjected to hardening and aging (or even double aging) before electrochemical treatment.

To exclude the loss of sealing elements due to their separation from the base of the insert during operation and to improve the sealing properties, the insert is filled with a sealing compound to a part of the height of the sealing elements.

It should be noted that, in comparison with the well-known traditional technologies for manufacturing brush seals (winding, winding or laying with subsequent welding, soldering or rolling of sealing elements - wires), the proposed technology is characterized by a high degree of automation and economy. In addition, the control of the parameters of the mode (voltage, EI feed rate, current pulse duration, electrolyte flow rate, etc.) with a pulsed ECM makes it possible to obtain various forms of the longitudinal profile of the sealing elements, for example, for reasons of imparting special bending and sealing properties.

In addition, the technology of pulsed ECHO compares favorably with the existing ones by insignificant thermal and mechanical effects on the workpiece, the absence of tool wear and the possibility of effective application in the processing of new types of steels and alloys that are difficult to process by traditional mechanical methods.

The absence of a welding operation and the implementation of the sealing elements in one piece with the base can improve the reliability of the seal, since it eliminates the possibility of thermally changed (defective) layers.

Concrete implementation example

Was made full-scale sample insert brush seal assembly with an annular segment by the proposed method.

For processing, we used a blank of an insert made of steel 20X13 (heat-treated to a hardness of HRC 40 ... 50) in the form of a rectangular parallelepiped of size (B × L × H) 8.5 mm × 80 mm × 7 mm. The process of electrochemical processing was carried out on a face with a size of 8.5 mm × 80 mm to a depth of 6.2 mm. As a result, a thin base with a thickness of c = 0.8 mm and a plurality of sealing elements located on it with a height of h = 6.2 mm was obtained.

The electrode tool was a thin (0.3 mm) perforated plate with round holes with a diameter of D = 0.45 mm, located at a distance of L _D = 0.65 mm from each other.

Parameters of the pulse ECHO mode:

- voltage in pulses U = 9 V;

- pulse duration f _u = 1.2 ... 1.4 ms;

- the frequency of the pulses f _u = 50 Hz;

- vibration frequency EI f _EI = 50 Hz;

- electrolyte pressure P _EL = 150 kPa.

Output Parameters:

- linear speed of formation (cutting) of the sealing elements V _EI = 32 ... 40 μm / min;

- ECHO process time f _ol = 175 min;

- the diameter of the sealing elements d = 0,31 ... 0,32 mm;

- the distance between the axes of the sealing elements l _d = L _D = 0,65 mm

The monolithic insert of the brush seal after the pulse ECHO is shown in Fig.7.

The resulting insert was bent with a radius of R = 200 mm and inserted into the seal housing in the form of an annular segment. The external view of the full-scale sample of the insert of the brush seal assembly with the annular segment obtained by the proposed method is shown in Fig. 8.

Thus, the proposed invention allows the manufacture of ring brush seals with the desired shape of the sealing elements and their clear relative position.

Claims (4)

1. A method of manufacturing a brush seal of an annular gap in the form of an annular housing, or a housing in the form of a set of annular segments and a monolithic insert, or a set of monolithic inserts, which are a base with a plurality of sealing elements located on them, which consists in forming by pulsed electrochemical processing on the treated surface each metal billet insert multiple sealing elements using the electrode tool, which is a perforated layer inu, followed by bending and securing each monolithic insert in a curved position in the annular housing or ring segments, which are subsequently connected to each other. 2. The method according to claim 1, characterized in that a wear-resistant coating with a thickness of 10 ÷ 20 μm more than is required to be obtained at the working ends of the sealing elements is applied to the treated surface of the insert blank before electrochemical treatment. 3. The method according to claim 1, characterized in that before the electrochemical treatment, hardening and at least one aging of the insert blank are carried out. 4. The method according to claim 1, characterized in that after electrochemical processing, the insert is poured with a sealing compound to a part of the height of the sealing elements.

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