RU2076085C1 - Method of fabricating seals - Google Patents

Abstract

FIELD: sealing technique. SUBSTANCE: graphite foil is prepared by rolling graphite powder, preliminarily subjected to thermoexpansion treatment, and separating contact surfaces with flexible porous tapes having regular microrelief on their surfaces. The thus obtained foil is cut into strips, which are crimped observing proportion of corrugation pitch to distance between corrugation ridges 0.2-20. Further, graphite strips are layer-by-layer wound onto press mold core and pressed. Invention may be applied in metallurgy, heat and nuclear power energetics, oil and gas engineering, machine tool industry, and automotive industry. EFFECT: improved procedure. 3 dwg

Description

 The invention relates to the field of metallurgy and relates to the manufacture of various types of stuffing box seals, gaskets, mechanical bearings operating at elevated temperatures and pressures, as well as in aggressive environments. The invention can be used in the fields of metallurgy, thermal and nuclear energy, oil and gas industry, engineering, automotive.

 A known method of manufacturing expanded graphite sheets to obtain seals from them (Japanese Application No. 1988-252151, class C 04 B 30/00, 1988), comprising producing sheets by pressure molding expanded graphite granules in a mold having a contact surface honeycomb structure or rolling in rolls of graphite granules on the surface of a horizontal plate of honeycomb structure, additional sheet forming and stamping from the resulting sheets of gaskets and seals. The known method provides increased tensile strength of the sheets, due to the creation of structures in these sheets in the form of honeycombs, which increases the operational stability of the seals made from the sheets.

 A known method of manufacturing seals, adopted as a prototype, US Patent, N 4068853, CL. 277-102), including cutting graphite foil from thermally expanded graphite into strips and pressing a graphite strip with its preliminary winding onto the mold rod. The known method provides high-performance batch production of seals with minimal waste. The disadvantage of this method is the insufficiently high operational stability of the seals due to the insufficiently high physical and mechanical properties of the material.

 The aim of the invention is to increase the operational stability of seals by increasing the strength and elastic properties of the material.

 This goal is achieved by the proposed method for the production of seals, which includes the production of graphite foil by rolling in a roll of thermally expanded powder with separation of the contact surfaces with a flexible porous tape with regular micro-relief on the surface, cutting the resulting foil into strips, corrugating the strips in the profile rollers to ensure the ratio of the corrugation step A to h the distance between the crests of the corrugations, equal to 0.2-20, and pressing the corrugated strip with preliminary layer-by-layer winding it on the rod of the mold.

 A certain microrelief of the tapes ensures a uniform distribution of its density along the perimeter of the resulting foil during rolling of the graphite powder, which increases the strength and elastic properties of the foil, and the porosity of the tapes ensures gas removal during rolling, which allows to obtain a high-quality surface without shells, delaminations and other internal defects.

 The corrugation of the strips provides a favorable distribution of the stress state diagram of the material, different in stress, which further improves the physical and mechanical properties of the material, i.e. strength and elastic properties of the material. In addition, the corrugation during subsequent pressing ensures reliable adhesion of the layers to each other, their mutual penetration, which also affects the improvement of the physico-mechanical properties of the seals.

 In FIG. 1 shows a diagram for producing graphite foil; in FIG. 2 - strip after corrugation; in FIG. 3 diagram of crimping a corrugated strip.

 The manufacture of seals is as follows.

 The graphite powder that has undergone thermal expansion processing is fed from the hopper 1 to the rolls 2, covered by flexible porous tapes 3 with a regular microrelief on the surface. The resulting foil is cut into strips. The stripes are corrugated with a ratio of A / h = 0.2-20, where A is the corrugation pitch, mm, h is the distance between the corrugations of the corrugations, mm. Next, the corrugated strip 4 is pressed with its preliminary winding onto the rod 5 of the mold.

The following are examples of the specific production of seals in the form of rings with an outer diameter of D _n = 32 mm, an inner diameter of D _ext = 22 mm and a height of h = 5 mm.

 Example 1

The thermally expanded graphite of the GSM-1 brand is fed into the rolling rolls covered by the tapes of their fabric with technical TSVM. The resulting foil with a thickness of 0.05 mm is cut into strips with a width of 35 mm, the strips are corrugated to ensure the ratio A / h = 0.2, then the strip is wound on the mold stock and pressed with a specific pressure of 250 kgf / cm ² .

 Example 2

GAK-1 thermally expanded graphite is fed into rolling rolls D = 300 mm, covered by flexible tapes in the form of technical TSVM fabric. The resulting foil with a thickness of 0.5 mm is cut into strips with a width of 35 mm, the strips are corrugated to ensure the ratio A / h = 20, then the strip is wound on the rod of the mold and pressed with a specific pressure of 250 kgf / cm ² .

 Example 3

The thermally expanded graphite of the GSM-1 brand is fed into rolls D = 300 mm, covered by ribbons made of technical TSVM fabric. The resulting foil with a thickness of 0.25 mm is cut into strips with a width of 35 mm, the corrugations are corrugated to ensure the ratio A / h = 0.15, the strip is wound on the rod of the mold and pressed with a specific pressure of 250 kgf / cm ² .

 Example 4

The thermally expanded graphite of the GT-1 brand is fed into rolls D = 300 mm, covered by ribbons made of technical TSVM fabric. The resulting foil with a thickness of 0.7 mm is cut into strips with a width of 35 mm, the strips are corrugated to provide an A / h = 22 ratio, then the strip is wound on the mold rod and pressed with a specific pressure of 250 kgf / cm ² .

 From the table it follows that the seals in examples 1 and 2 have 2 times higher shear and break strength compared with the prototype, and also 2 times higher recoverability after unloading.

 Seals in examples 3 and 4 have parameters close to the prototype, which implies that the corrugation, especially when ensuring the optimal A / h ratio, significantly affects the strength and elastic properties of the seal material.

 The technical and economic effect of the proposed method consists in the fact that the seals obtained by this method have the ability to maintain shape stability at sharp temperature changes, high tightness, they are chemically inert when in contact with aggressive environments, environmentally friendly when used.

Claims (1)

 A method of manufacturing seals, including cutting foil from thermally expanded graphite into strips, crimping and pressing a graphite strip with pre-layer-by-layer winding it onto the mold rod, characterized in that the foil is produced by rolling graphite powder in rolls with separation of the contact surfaces by flexible porous tapes with regular micro-relief on the surface, and the corrugation is carried out with a ratio of the step of the corrugation to the distance between the crests of the corrugations, equal to 0.2 20.

Images