RU2186273C1 - Method of manufacture of flat sealing gasket - Google Patents

Abstract

FIELD: sealing technology; fuel-and-power complexes, atomic power plants, automobile and chemical industries and space engineering; metallurgy; sealing joints and flange connectors. SUBSTANCE: proposed method includes shaping the gasket by spirally laying turns of foil on base of thermal split graphite and molding; of foil at density of 0.5 to 0.8 g/cu.cm are laid, after which turns of foil at density of 1.0 to 1.5 g/cu.cm are laid; shaping of sealing foil is completed by laying turns of foil at density of 0.5 to 0.8 g/cu.cm and then molding is performed at specific pressure of 450 to 500 kgf/sq.cm maintaining this pressure for 0.5 to 1 min. EFFECT: improved operating characteristics; increased service life; enhanced tightness and reliability of joints. 2 cl, 1 dwg

Description

 The invention relates to sealing equipment and can be used in the fuel and energy industry, nuclear power plants, the automotive, chemical, metallurgical, and space industries for sealing joints and connectors of flanged and other joints and interfaces.

A known method of manufacturing a sealing gasket from foamed graphite (a.a. USSR 1525384, MKI F 16 J 15/12), which uses not powder of foamed (thermally split) graphite, but its preformed mass with a density of 0.2-1.2 g / cm ³ . This mass is then processed into pieces, from which gaskets are made by compression into a “blank matrix”.

 The disadvantage of the gasket in this case is its low mechanical characteristics, and the manufacturing method is quite simple.

 A known method of manufacturing a sealing material, comprising connecting a tape of graphite foil on one or both sides with flexible or flexible tapes using an adhesive layer, after which the resulting tape is wound on a thread, forming a filiform material (RF patent 2043556, MKI F 16 J 15 / 00, 1995).

 The disadvantage of this method is its technical complexity, in addition, at elevated temperatures, the sealing material exfoliates, since the adhesive layer has a low operating temperature.

 A known method of manufacturing a flat sealing gasket, including rolling graphite tape, deformation of the tape with a constant step by bending its sections in opposite directions with the formation of corrugations, compressing the corrugations to the contact of their blades, placing the formed tape in the groove under the gasket of the sealing joint and pressing in the tightening mode bolts of a sealed joint (RF patent 2072459, MKI F 16 J 15/12, 1997).

 The disadvantage of this method is that the manufactured seal acts as an stuffing box and can be used only once in a particular place. In this case, layering of the gasket is possible due to the lack of adhesion between the corrugation blades.

 A known method of manufacturing a flat sealing gasket for the sealing unit of the rod of shut-off and control valves, including forming a gasket (sealing ring) by laying in a spiral of turns (tape) of foil based on expanded (thermally split graphite) and pressing (rolling) (RF patent 2065109, MKI F 16 J 15/30, 1996 - prototype). The tape is cut from expanded graphite foil in a direction perpendicular to the rolling direction.

 The disadvantage of this method is the reduced performance due to the heterogeneity of the strip density. In addition, the gasket made by this method is used once at the place of manufacture.

 The technical result of the proposed solution is to increase the operational characteristics of the gasket, namely to increase the service life, tightness and reliability of the joints, reduce energy losses, increase the time of trouble-free operation, improve the environment by reducing harmful emissions.

The specified technical result is achieved by the fact that in the known method of manufacturing a flat sealing gasket, including the formation of the gasket by laying in a spiral spiral of foil based on thermally split graphite and pressing, first they are laying the coil of foil with a density of 0.5-0.8 g / cm ³ then the laying of the foil turns with a density of 1.0-1.5 g / cm ^{3 is} carried out, after which the laying of the laying of the foil turns with a density of 0.5-0.8 g / cm ^{3 is completed} and then pressing is performed at a specific pressure of 450 500 kg / cm ² s under pressure for 0.5-1 min.

 To ensure increased adhesion between the layers during the installation of the foil turns, the gaps between the foil turns are filled with thermally split graphite powder. This process can be followed by shaking to form a tighter contact between the turns of the foil.

 The proposed technical solution is industrially applicable and can be used in the sealing technique of nuclear and thermal power plants, chemical, space and defense industries, since the main distinguishing features of new seals based on graphite foil is their environmental cleanliness, significantly higher reliability when operating equipment in extreme conditions (elevated temperatures, aggressive environments, increased pressure, etc.) compared with traditional asbestos (to Cancer) Gaskets.

 The invention consists in the following.

When forming gaskets by pressing into a “blank die”, it is difficult to achieve equidistance across the entire thickness of the gasket. In the proposed method, equal density is achieved by placing in the center of the strip of turns of foil with a density close to the final (1.0-1.5 g / cm ³ ), on the surfaces of the strip, on the contrary, are placed turns of foil with a low density (0.5- 0.8 g / cm ³ ), which will acquire a given high density during the pressing process.

 To prevent delamination of the gasket between the turns of the foil, a thermally split graphite powder is placed, providing tight contact, good adhesion and adhesion of the turns of the foil to each other.

 The following are examples of a method for manufacturing a flat gasket.

 Example 1

The foil based on thermally split graphite with a density of 0.8, 1.5, 0.8 g / cm ³ , made by rolling between the rollers, was cut into strips of a given width and laid in a spiral: first, foil with a density of 0.8 g / cm was laid ³ , then with a density of 1.5 g / cm ³ , after which the laying of the foil turns with a density of 0.8 g / cm ^{3 was completed} and pressing was performed under a pressure of 500 kg / cm ² . Exposure at maximum pressure was 1 min.

 Example 2

The manufacture of the gasket was carried out according to example 1 with a density of turns of foil of 0.5, 1.0, 0.5 g / cm ³ . The pressing pressure was 450 kg / cm ² , exposure at maximum pressure was 0.5 min.

 Example 3

The manufacture of the gasket was carried out according to example 1 with a foil density of 0.6, 1.2, 0.6 g / cm ³ . The pressing pressure was 500 kg / cm ² , exposure at maximum pressure was 1 min.

 Example 4

The manufacture of the gasket was carried out according to example 1 with a density of turns of foil 0.8, 1.5, 0.8 g / cm ³ , and the gaps between the turns of the foil were filled with thermally split graphite powder with a bulk density of 2-10 g / liter. The pressing pressure was 500 kg / cm ² , holding at a maximum pressure of 0.5 minutes

 The test results of the gasket made by the prototype method and the proposed method are presented in the table.

 As can be seen from the table, the operational characteristics of the gaskets made according to examples 1-4 exceed the prototype in terms of uniformity, mechanical strength, and such basic parameters as recoverability, compressibility, characterizing the operability of the seals and ensuring the tightness of the assembly in which they are operated, as well as affecting the increase in the resource of their work.

 The proposed gaskets, in addition to the indicated applications, can be used in gas and thermostats, in centrifugal pumps, as well as in oil refining and distillation equipment, namely, when sealing boiler covers, flanges, nozzles, cuffs, etc.

Claims (2)

1. A method of manufacturing a flat sealing gasket, comprising forming a gasket by spirally wrapping the foil turns on the basis of thermally split graphite and pressing, characterized in that the foil turns with a density of 0.5-0.8 g / cm ³ are laid first, then laying turns of foil with a density of 1.0-1.5 g / cm ³ , after which the formation of the sealing gasket is completed by laying turns of foil with a density of 0.5-0.8 g / cm ³ and pressing is performed at a specific pressure of 450-500 kg / cm ² with exposure under pressure for 0.5-1 min.  2. The method according to p. 1, characterized in that in the process of laying the turns of the foil, the gaps between the turns of the foil are filled with thermally split graphite powder.

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