JP2005282772A - Gland packing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gland packing having an excellent sealability and an excellent heat-resistance. <P>SOLUTION: The gland packing is comprised of a metallic coil spring and an expanded graphite cladding layer which is formed by braiding it using an expanded graphite knitting yarn to surround the outer circumferential surface of the metallic coil spring. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a novel gland packing that is mounted in a stuffing box such as a rotary pump, a valve, a stirrer, and a reciprocating pump and seals a stem or the like in the stuffing box.

  Conventionally, as the gland packing, for example, an asbestos yarn braided and impregnated with a lubricant or the like, or an asbestos, a lubricant and a binder are kneaded and formed by extrusion or pressing are known. Asbestos has been widely used as a material for gland packing because of its excellent thermal stability and wear resistance, and excellent retention of lubricants and adhesives. However, asbestos causes problems such as pneumoconiosis and is not preferable in terms of environmental hygiene, so its use has been restricted recently.

  Therefore, in recent years, packing using expanded graphite having a good sealing property as a main raw material has been used instead of asbestos. There are various types of expanded graphite packing. The most common type is a tape-shaped material obtained by slitting an expanded graphite sheet to a predetermined width, and a spiral or concentric circle in a molding die. It is a ring-shaped gland packing obtained by compressing and molding this in the longitudinal direction after being arranged in a shape.

  In addition, as an expanded graphite packing having a different structure, expanded graphite and reinforcing fibers can be formed by a method such as bag knitting with reinforcing fibers around a tape-shaped material obtained by slitting an expanded graphite sheet to a predetermined width. By making a knitted yarn that is compounded and braiding it into eight knitting, bag knitting, lattice knitting, etc., and forming a string-like body, it can be used by cutting to a predetermined length according to various shaft diameters The braid type is also used recently.

  Such expanded graphite-based packing is used in various sizes according to the size of the stuffing box. Among them, as shown in FIG. 5, the core 102 and the outer peripheral surface 102a are surrounded. As described above, the packing 100 including the expanded graphite coating layer 106 formed by braiding with the expanded graphite knitting yarn 104 is widely used. As the core 102, a bundle of braided yarns made of expanded graphite and reinforcing fibers or a braided one, or a bundle of inorganic fibers or organic fibers or a braided one is used.

However, since such a core has no elasticity, there is a problem that a gap is easily generated between the core and the knitting yarn, and the sealing performance of the packing is lowered.
In order to solve such a problem, a gland packing in which a core is formed of a mixture containing fibers, rubber, and a filler has been proposed (see, for example, Patent Document 1). However, since such a gland packing contains rubber which is an elastic body in the core, the sealing performance is improved, but there is a problem in heat resistance. Therefore, in a device used at a high temperature such as a main steam valve of a thermal power plant, a gland packing excellent in both sealing performance and heat resistance has been demanded.
JP 2001-32944 A

  An object of the present invention is to provide a gland packing that is excellent in sealing properties and heat resistance.

The present invention was invented in order to achieve the problems and objects in the prior art as described above,
[1] The gland packing according to the present invention includes a metal coil spring and an expanded graphite coating layer formed by braiding with an expanded graphite knitting yarn so as to surround the outer peripheral surface of the metal coil spring. It is characterized by.

Thus, the gland packing of the present invention uses the metal coil spring as the center, and the load from one direction is effectively applied to the other direction of the gland packing by the elastic force of the metal coil spring. Can tell. Therefore, the gland packing of the present invention can exhibit excellent sealing properties. Furthermore, since the gland packing of the present invention uses a metal coil spring, it is excellent in heat resistance. Therefore, it can be used for a sealing device of a device used at a high temperature such as a main steam valve of a thermal power plant.
[2] The coating layer is formed by braiding an outer periphery reinforced expanded graphite knitting yarn having a reinforcing material provided on the outer periphery of expanded graphite and an inner reinforced expanded graphite knitting yarn having a reinforcing material provided inside the expanded graphite. The gland packing according to [1], which is formed.
[3] The gland packing according to [1], wherein the covering layer is formed by braiding an outer peripheral reinforcing expanded graphite knitting yarn provided with a reinforcing material on an outer periphery of the expanded graphite.

By using the expanded graphite knitting yarn whose outer periphery is reinforced, even if the gold wires of the metal coil springs are separated from each other by a predetermined distance, a part of the expanded graphite knitting yarn may protrude into the hollow portion of the coil spring. Absent. Therefore, the gland packing does not cause stress relaxation and can exhibit further excellent sealing performance.
[4] A ring-shaped gland packing according to the present invention is characterized in that the gland packing according to any one of [1] to [3] is formed into a ring shape.

Since the ring-shaped gland packing has a metal coil spring as a core, when it is used as a gasket of a sealing device, the replacement work is easy. Therefore, the maintenance work of the sealing device can be performed quickly and easily.
[5] The sealing device of the present invention includes a stuffing box formed so as to surround the outer peripheral surface of the shaft,
The ring-shaped gland packing according to [4], which is laminated so as to seal between the shaft and the stuffing box;
Packing holding means for pressing the ring-shaped gland packing in the axial direction;
It is characterized by having.

  In such a sealing device of the present invention, when the ring-shaped gland packing is pressed in the axial direction by the packing pressing means, the pressure is caused by the elastic force of the metal coil spring, and the inner and outer circumferential surfaces of the ring-shaped gland packing. Effectively communicated to the surface. Therefore, the ring-shaped gland packing can exhibit excellent sealing performance. Furthermore, since the sealing device of the present invention uses a ring-shaped gland packing whose core is a metal coil spring, it has excellent heat resistance, such as a main steam valve of a thermal power plant used at high temperatures. It can be applied to the device.

  ADVANTAGE OF THE INVENTION According to this invention, the gland packing which is excellent in sealing performance and excellent in heat resistance can be provided. Therefore, it can be used for a sealing device in a device used at a high temperature such as a main steam valve of a thermal power plant.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings.
In addition, when showing the same part in each drawing, the same code | symbol is described.
1 is a cross-sectional perspective view of the gland packing of the present invention, FIG. 2 is a partially cutaway view of the ring-shaped gland packing of the present invention, and FIG. 3 is a schematic longitudinal cross-sectional view of the sealing device of the present invention.

  As shown in FIG. 1, the gland packing 10 of the present invention includes a metal coil spring 12 and an expanded graphite coating layer 15 formed by braiding with an expanded graphite knitting yarn 14 so as to surround the outer peripheral surface 12a. Consists of.

  Thus, the gland packing 10 uses the metal coil spring 12 as the center, and the load from one direction is effectively applied to the other direction of the gland packing by the elastic force of the metal coil spring. I can tell you. Therefore, the gland packing of the present invention is excellent in sealing performance. Furthermore, since the gland packing 10 uses a metal coil spring, it is excellent in heat resistance. Therefore, it can be used for a sealing device of a device used at a high temperature such as a main steam valve of a thermal power plant.

  The metal coil spring 12 is not particularly limited, and any metal coil spring can be used. However, as shown in FIG. 1, the metal wires are in contact with each other. Thus, it is preferable to use a substantially cylindrical coil spring wound in a spiral shape. The metal wire may have any shape having a substantially circular cross section or a substantially rectangular cross section.

  By using such a metal coil spring 12, it is possible to prevent a part of the expanded graphite knitting yarn 14 from protruding into the hollow portion 16 of the metal coil spring 12. Therefore, the obtained gland packing does not cause stress relaxation and can exhibit excellent sealing properties. The metal coil spring 12 is made of spring steel, alloy tool steel, austenitic stainless steel, precipitation hardened stainless steel, maraging steel, Ni-base superalloy, Ni-Co superalloy, titanium, or the like.

  The hollow portion 16 of the metal coil spring 12 may be filled with a filler. By prefilling the filler, it is possible to effectively prevent a part of the expanded graphite knitting yarn 14 from protruding into the hollow portion 16 of the metal coil spring 12 when the gland packing is used. be able to. Therefore, the obtained gland packing does not cause stress relaxation and can exhibit further excellent sealing performance.

  Examples of such a filler include organic fibers such as aramid fibers, polyacrylonitrile fibers, polyamide fibers, polyolefin fibers, and fluororesin fibers; inorganic fibers such as metal fibers, rock wool, carbon fibers, and glass fibers; various rubbers Materials such as graphite, expanded graphite, and scaly graphite; vermiculite, talc, mica, and the like can be used, and one or more can be used in combination.

On the other hand, the expanded graphite coating layer 15 is formed by braiding the expanded graphite knitting yarn 14 so as to surround the outer peripheral surface 12 a of the metal coil spring 12.
As the expanded graphite knitting yarn 14, an outer peripheral reinforced expanded graphite knitting yarn in which a reinforcing material is provided on the outer periphery of the expanded graphite, and an internally reinforced expanded graphite knitting yarn in which the reinforcing material is provided inside the expanded graphite are used. Are used in appropriate combinations so as to pass through.

As the outer peripheral reinforcing expanded graphite knitting yarn, a plurality of strip-shaped expanded graphite sheets having a thickness of about 0.2 to 1.0 mm and a width of about 2.0 to 10.0 mm are laminated, and the surface thereof is a high-strength fiber as described later. And knit knitted or bag knitted, or those obtained by spirally winding the outer periphery of expanded graphite with a fine metal wire or the like. The expanded graphite used for the outer peripheral reinforcing expanded graphite knitting yarn preferably has a carbon content of 96.5 or more and a density of 0.5 g / cm ³ or more. In addition, as the high-strength fiber, a fiber having a strength of 50 MPa or more is used, and specific examples include carbon fiber, metal fiber, aramid fiber, glass fiber, ceramic fiber, and the like. The fiber diameter of such a high-strength fiber is usually 0.1 to 10 μm. Stainless steel, copper alloy,
Examples of the metal wire include aluminum alloy, monel, and inconel, and have a diameter of 0.1 to 0.3 mm.

The internally reinforced expanded graphite knitting yarn may be a knitted yarn obtained by folding a strip-shaped expanded graphite sheet, and a strip-shaped expanded graphite sheet is laminated and coated on a metal foil having a thickness of about 0.005 to 0.2 mm. A knitting yarn in which a strip of expanded graphite is spirally wound or twisted around a high-strength fiber such as a thin metal wire having a thickness of about 0.1 to 0.3 mm or an aramid fiber. There may be. The expanded graphite used for the internally reinforced expanded graphite knitting yarn has a carbon content of 96.5.
As described above, those having a density of 0.5 g / cm ³ or more are preferable.

  In the present invention, it is preferable to use a peripheral reinforcing expanded graphite knitting yarn as the expanded graphite knitting yarn 14. By using the outer periphery reinforced expanded graphite knitting yarn whose outer periphery is reinforced, a part of the expanded graphite knitting yarn 14 does not protrude into the hollow portion 16 of the metal coil spring 12. Therefore, the obtained gland packing does not cause stress relaxation and can exhibit excellent sealing properties.

  The gland packing 10 of the present invention is manufactured by bagging an expanded graphite knitting yarn 14 so as to surround an outer peripheral surface 12a of a metal coil spring 12, and forming an expanded graphite coating layer (square braid) 15. The

  In the present invention, as shown in FIG. 1, the gland packing using one coil spring 12 has been described as an example. However, the gland packing may be formed using a plurality of coil springs. Specifically, as shown in FIG. 4 (a), a plurality of coil springs are arranged at a substantially central portion (center), and a central packing as shown in FIG. 4 (b). A gland packing arranged at four corners can be exemplified.

  Such a gland packing 10 of the present invention is not particularly limited, but is preferably used after being pressure-molded into a ring shape. Specifically, the gland packing 10 is manufactured by cutting the gland packing 10 with a predetermined dimension and compression-molding it into a ring shape by a usual method, and a ring-shaped gland packing 20 as shown in FIG. 2 is obtained. Since the ring-shaped gland packing 20 is formed from the gland packing 10 having the metal coil spring 12 at the center, the ring-shaped gland packing 20 is excellent in sealing performance and heat resistance.

  On the other hand, the conventional ring-shaped gland packing (gasket) made of expanded graphite alone has excellent heat resistance, but its strength is low, and when the gasket is replaced after pressing, the graphite is broken apart. End up. For this reason, the gasket could not be easily taken out and replacement work was difficult. On the other hand, since the ring-shaped gland packing of the present invention has a metal coil spring as a core, it can be easily taken out by hooking a predetermined packing taking-out jig on the spring. Therefore, when the ring-shaped gland packing 20 of the present invention is used as a gasket for a sealing device, the replacement operation is easy, so that the maintenance operation of the sealing device can be performed quickly and easily.

The sealing device of the present invention is provided with such a ring-shaped gland packing 20. Specifically, as shown in FIG. 3, the sealing device 30 includes a stuffing box 36 formed so as to surround the outer peripheral surface 34 of the shaft 32, and a seal between the shaft 32 and the stuffing box 36. As shown, the ring-shaped gland packing 20 connected to the outer peripheral surface 34 of the shaft 32 and packing pressing means 38 for pressing the ring-shaped gland packing 20 in the axial direction are basically provided.

  Further, the packing pressing means 38 is fixed to the stuffing box 36 by the fixing means 40, and the ring-shaped gland packing 20 is pressed against the outer peripheral surface 34 of the shaft 32 in the stuffing box 36 so that a desired pressure is obtained. It has become so.

  The ring-shaped gland packing 20 of the present invention uses a metal coil spring 12 as the center. Therefore, when the ring-shaped gland packing 20 is pressed in the axial direction by the packing pressing means 38, the pressure is effectively transmitted to the inner side surface 20 a and the outer side surface 20 b by the elastic force of the metal coil spring 12. These surfaces are pressed against the outer peripheral surface 34 of the shaft 32 and the inner peripheral surface of the stuffing box 36, respectively. Therefore, the ring-shaped gland packing 20 can exhibit excellent sealing performance. Furthermore, since a metal coil spring is used for the core, heat resistance is also excellent.

  Such a sealing device of the present invention can be used for devices such as rotary pumps, valves, stirrers and reciprocating pumps, rotary devices, reciprocating devices, etc., and has particularly high heat resistance such as a main steam valve of a thermal power plant. Even in the required apparatus, excellent sealing performance and heat resistance can be exhibited.

In the present embodiment, the ring-shaped gland packing according to the present invention has been described as an example using a sealing device as shown in FIG. 3, but the shape of the sealing device is not particularly limited.
As described above, various modifications can be made without departing from the object of the present invention.

FIG. 1 shows a cross-sectional perspective view of the gland packing of the present invention. FIG. 2 shows a partial cutaway view of the ring-shaped gland packing of the present invention. FIG. 3 shows a schematic longitudinal sectional view of the sealing device of the present invention. FIG. 4 shows a cross-sectional perspective view of a gland packing in another embodiment of the present invention. FIG. 5 shows a cross-sectional perspective view of a conventional gland packing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,100 Gland packing 12 Metal coil spring 14 Expanded graphite knitting yarn 15, 106 Expanded graphite coating layer 16 Hollow part 20 Ring-shaped ground packing 20a Inner peripheral surface of ring-shaped ground packing 20b Outer peripheral surface of ring-shaped ground packing 30 Sealing device 32 shaft 34 outer peripheral surface of shaft 36 stuffing box 38 packing holding means 40 fixing means 102 center core 102a outer periphery surface of center core 104 expanded graphite knitting yarn

Claims (5)

  A gland packing comprising a metal coil spring and an expanded graphite coating layer formed by braiding an expanded graphite knitting yarn so as to surround an outer peripheral surface of the metal coil spring.   The covering layer is formed by braiding an outer peripheral reinforcing expanded graphite knitting yarn in which a reinforcing material is provided on the outer periphery of expanded graphite and an inner reinforcing expanded graphite knitting yarn in which the reinforcing material is provided inside the expanded graphite. The gland packing according to claim 1, wherein:   The gland packing according to claim 1, wherein the covering layer is formed by braiding an outer peripheral reinforcing expanded graphite knitting yarn provided with a reinforcing material on an outer periphery of the expanded graphite.   A ring-shaped gland packing obtained by compression-molding the gland packing according to any one of claims 1 to 3 into a ring shape. A stuffing box formed so as to surround the outer peripheral surface of the shaft;
The ring-shaped gland packing according to claim 4 laminated so as to seal between the shaft and the stuffing box,
Packing holding means for pressing the ring-shaped gland packing in the axial direction;
A sealing device characterized by comprising:

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