GB2243883A

GB2243883A - Braided sealing cord

Info

Publication number: GB2243883A
Application number: GB9109654A
Authority: GB
Inventors: Hans J Tuckmantel
Original assignee: Kempchen and Co GmbH
Current assignee: Kempchen and Co GmbH
Priority date: 1990-05-08
Filing date: 1991-05-03
Publication date: 1991-11-13
Anticipated expiration: 2011-05-03
Also published as: GB9109654D0; DE4014719C2; BE1006762A5; FR2661967A1; NL194805B; DE4014719A1; JPH04228974A; GB2243883B; FR2661967B1; NL194805C; NL9100790A

Abstract

A braided sealing cord (1) for packed seals, more particularly for stuffing box packings, consisting of a plurality of sealing card elements (2) The sealing cord elements (2) consist of graphite strips (5) taken from a sealing graphite foil, the graphite strips being surrounded by a braiding (4) of relatively thin braiding elements. The graphite strips may be braided or lie parallel to each other and the card elements 2 are braided together. <IMAGE>

Description

:2:2-4;3 a a;:3 BRAIDED SEALING CORD This invention relates to a braided

sealing cord for packed seals, more particularly for stuffing box packings, consisting of a plurality of sealing cord elements having a graphite core.

A sealing cord can be an elongated component having sufficient strain capacity to be formed into a packed seal. Alternatively however, the sealing cord can be folded into a ring and if required into a continuous coil. Sealing cords in general are more or less square or rectangular in cross- 'section. They are used for seals on shafts, connecting rods, armatures, valve stems, expansion joints and other escape orifices from pressurised spaces.

In the braided sealing cord to which the invention relates, the sealing cord elements are yarns, as defined in textiles technology, in which graphite is embedded to act additionally as a lubricant (cf. US 3 646 846). They are braided together and consist of a suitable sealing material such as asbestos fibres, glass fibres, carbon fibres, graphite fibres, polytetrafluorethylene fibres and/or aramide fibres, optionally impregnated with other substances. The known sealing cords are adequate from the sealing technology viewpoint, but are open to improvement in thermal durability respects. Thermal durability denotes stability at elevated temperatures in the working environment, under the designrelated mechanical loads and the loads related to the environment.

A basic object of the invention is to provide a 2 braided sealing cord of the type initially described that is outstandingly improved with respect to its superior thermal durability.

According to the present invention, there is provided a braided sealing cord for packed seals, more particularly for stuffing box packings, comprising a plurality of sealing cord elements having a braided graphite core consisting of at least one graphite strip torn from a graphite foil made from sealing graphite, the graphite cores being braided three dimensionally.

The cross-section section, for example more or less circular Graphite is known as a sealing material.

graphite strips can have a rectangular or square but preferably they have a rounded crossor elliptical. More particularly, graphite is used as a sealing material in the form of consolidated expanded graphite in graphite foil form. its thermal durability range in suitable atmospheres extends from 0 0 minus 250 C to plus 2500 C. It has hitherto been impossible to use sealing graphite for braided sealing cords of the type initially described and for the purposes initially outlined, because of its mechanical shortcomings, notably its inadequate tensile strength. These are surprisingly overcome in the sealing cord structure of the invention, and the braided sealing cores in situ exhibit an astonishingly high thermal durability.

There are various possibilities for further improvement and adaptation of -the invention in detailed respects. Thus, by arranging a plurality of graphite strips Y 1 1 in a single graphite core, the graphite strips can be built UP into a strip assembly of parallel graphite strips. In a preferred embodiment of the invention having a plurality of graphite strips arranged in a single graphite core, the graphite strips are built up to form a string. In every case, the graphite strips in the graphite core can exhibit a twist and/or be twisted round each other.

It is also within the scope of the invention to use a variety of materials for the braid elements. Their function is to stabilise the sealing cord mechanically until it is placed in situ. The braid elements can consist of metallic and/or textile materials, such as graphite silk, or even some synthetic material. In order to make the sealing cord as a whole flexible, it is preferable to provide the graphite strips and/or the graphite cores with a coating of some lubricant. The coating can be thin. Itcan also be applied by spraying. More particularly, lubrication graphite can be used.

The invention will now be described in more detail, with reference to a schematic drawing of embodiments thereof, purely by way of example. In the drawing:

Figure 1 is a cross-section through a braided sealing cord of the invention; Figure 2 is a plan view of a graphite foil having tear-off graphite strips; Figure 3 shows a braided graphite core, in elevation and cross-section; and Figure 4 shows another embodiment of a braided 4 graphite core, in the same views as Figure a.

The braided -sealing cord 1 shown in the drawings in cross-section and having the components described above, is adapted for making packed seals, more particularly stuffing box packings. It consists of a plurality of sealing cord elements 2, which themselves consist of graphite cores 3 made from sealing graphite. The graphite cores 3 have a braiding 4 of braiding elements which are thin compared with the graphite cores 3. The braided graphite cores 3 themselves are braided three-dimensionally to form the cord, so that the cross-section shown in Figure 1 is produced. Figure 1 is an enlarged cross-sectional view, to clarify the structure of the sealing cord 1.

Figure 2 shows that the graphite cores 3 can be built up from graphite strips 5 torn from a graphite foil 6 made from sealing graphite. It is indicated in Figure 2 that the graphite strips 5 have a rectangular crosssection. According to Figure 3, the graphite strips 5 are rounded, and in fact have a more or less circular cross-section. Figure 3 further shows that a plurality of the graphite strips 5 form a single graphite core, the graphite strips 5 being built up into a strip assembly of parallel graphite strips 5. Figure 4 on the other hand shows the graphite strips 5 built up to form a string. The graphite strips 5 could in every case exhibit a twist and be twisted more or less strongly around each other.

The braiding 4, which can be seen in both Figure 1 and Figures 3 and 4, consists of metal or a textile material, 1 1 including for example synthetic materials. If metallic, it can consist of wires. If a textile material is used, it can be a synthetic monofilament or a yarn.

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Claims

1. A braided sealing cord for packed seals, more particularly for stuffing box packings, comprising a plurality of sealing cord elements having a braided graphite core consisting of at least one graphite strip torn from a graphite foil made from sealing graphite, the graphite cores being braided three- dimensionally.

2. A braided sealing cord as in Claim 1, wherein the graphite strip(s) has a rounded cross-section.

3. A braided sealing cord as in either of Claims 1 and 2, wherein a plurality of graphite strips are arranged in a single graphite core, the graphite strips being built up into a strip assembly of parallel graphite strips.

4. A braided sealing cord as in any of Claims 1 to 3, wherein a plurality of graphite strips are arranged in a single graphite core, the graphite strips being built up to form a string.

5. A braided sealing cord as in any of Claims 1 to 4, wherein the graphite strips in the graphite core exhibit a twist and/or are twisted round each other.

6. A braided sealing cord as in any of Claims 1 to 5, wherein the graphite strips and/or the graphite cores have a lubricant coating.

7. A braided sealing cord as in any of Claims I to 6, wherein the braiding consists of metallic and/or textile materials, more particularly synthetic.

8. A braided sealing cord substantially as hereinbefore described with reference to Figures 1, 2 and 3 of the accompanying drawings.

9. A braided sealing cord substantially as hereinbefore described with references to Figures 1, 2 and 4 of the accompanying drawings.

1 1 Published 1991 at The Patent Office, Concept House, Cardiff Road, Newport, Gwent NP9 I RH. Further copies may be obtained from Sales Branch, Unit 6. Nine Mile Point, Cwrnfelinfach, Cross Keys, Newport. NP I 7HZ. Printed by Multiplex techniques lid. St Mary Cray, Kent.