JPH082531Y2 - Gland packing - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a gland packing for sealing a rotary shaft such as a valve stem or a pump or a reciprocating shaft such as a cylinder device.

Technical background of the invention The gland packing is, for example, incorporated in the valve stem which operates the valve. The valve stem 1 shown in FIG. 6 is provided by inserting the stuffing box 2.
A gland packing g for sealing between the valve stem 1 and the stuffing box 2 is incorporated in the stuffing box 2.

The gland packing g is formed by stacking four ring-shaped single bodies 3, and hard rings 4 and 4 are provided at both ends of the gland packing g. The gland packing g is fixed and held via a packing presser 6 by tightening bolts 5 and 5.

Since the gland packing g is in sliding contact with the valve stem 1, it is desirable that the gland packing g is excellent not only in its original function of sealing, but also in lubricity with the valve stem 1.

Therefore, the gland packing g used to seal the valve stem 1 has a conventional asbestos thread coated with a binder made of a rubber solvent containing graphite and is knitted into a tubular material. There is one that is cut into pieces and formed into an annular shape in a die (see Japanese Patent Publication No. 41-20161).

However, this gland packing g has the asbestos yarn and the binder even inside the braided body, so that the gland packing g has poor elasticity as a gland packing g, the fluid sealing property is insufficient, and it is not preferable for environmental hygiene. Due to the use of cotton threads, their use has recently been severely restricted.

Therefore, in order to improve the lubricity of a recent gland packing, various fibers, for example, carbon fibers, fluororesin fibers, or other fiber yarns are used to form a long length by a braiding method such as lattice knitting, eight knitting, and bag knitting. It is manufactured by cutting a long string-like body to obtain a cut piece, forming both ends of the cut piece in a ring shape opposite to each other, and compression-molding this in a mold.

However, in such a gland packing, the end of the cut piece obtained by cutting the string-like body in which the fiber yarn is braided has the fiber piece 7 protruding as shown in FIG.
Fraying is liable to occur, and when used in the stuffing box 2 in such a frayed state, abrasion powder of the fiber yarn is generated, which may be mixed in the fluid to be sealed.
For example, when the gland packing is used as a seal for a stirring shaft of a reactor such as a polymer, if the abrasion powder is generated, a product in which foreign matter is mixed is obtained.

Further, in order to prevent the fraying, it is possible to wind a tape around the end of the ring body, but even if such a tape is wound, the tape peels off during use, and as a result, the braid There is a problem that fraying cannot be prevented.

DISCLOSURE OF THE INVENTION The present invention is intended to solve the problems associated with the prior art as described above, and eliminates fraying at the end of a cut piece obtained from a string-like body in which fiber threads are braided. The purpose of the present invention is to provide a gland packing that does not generate abrasion powder of fiber yarn during use.

SUMMARY OF THE INVENTION The gland packing according to the present invention is a gland packing formed by cutting a long string-like body formed by braiding fiber yarns into ring-shaped pieces having opposite end surfaces facing each other. In the above, the end of the cut piece is covered with a heat-shrinkable film.

According to the gland packing according to the present invention, even when the shaft is sealed by putting it in a stuffing box or the like, the heat-shrinkable film prevents fraying at the end of the cut piece, and abrasion powder of the fiber yarn is generated. There is no possibility that it will occur or this will be mixed into the fluid to be sealed.

Further, if the portion to be cut of the string-like body is temporarily fixed with a tape, fraying does not occur when the string-like body is cut.

In particular, when the end of the cut portion is covered with a heat-shrinkable film, if even a part or the whole of the end face is covered, the protrusion of the fiber yarn is almost completely prevented from this end face, and when the gland packing is used, the fiber yarn is It is possible to more reliably prevent the generation of abrasion powder.

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing a gland packing according to an embodiment of the present invention, and FIGS. 2 to 5 show working steps in the case of covering the end portion of a cut piece with a heat-shrinkable film at the time of manufacturing the gland packing. FIG.

The gland packing G according to the present invention comprises, as shown in FIG. 1, a cut piece 9 of a predetermined length in which fiber threads are braided. The cut piece 9 is obtained by cutting a long string-like body 10 (see FIG. 2).

The cord-like body 10 uses a core material in which a plurality of fiber threads are bundled or twisted together, and the outer circumference thereof is covered with a bag shape formed by braiding the fiber threads with a braiding machine. To be formed. In addition, this string-like body 10
May have other configurations, for example, the packing material in which the outer circumference of the fiber yarn braided by a braiding machine is similarly covered with a bag-shaped one and used as a packing material. You can also

As the fiber thread used for the packing material, for example, carbon fiber, fluororesin fiber, phenol resin fiber,
There are aramid fibers, metal fibers, cotton threads, and the like, and as a method of braiding with a braiding machine to form the string-like body 10, generally, lattice knitting, eight knitting, bag knitting, and the like are used.

The cutting piece 9 is obtained by cutting the cord-shaped body 10 formed in this manner, as shown in FIG. 3, in a plane perpendicular to the axis line so as to have a length corresponding to the outer circumference of the shaft to be sealed. Manufactured. In this case, preferably, before cutting, it is desirable to wind the tape 11 around the part to be cut and temporarily fix it. If the part to be cut in advance is temporarily fixed, the braid will not be unraveled after cutting, and fraying at the end 10a of the string-like body 10 and the end 9a of the cut piece 9 can be prevented.

As the tape 11 used for this temporary fixing, a cellophane tape or an unfired tape of a tetrafluoroethylene resin is preferable.

After this temporary fixing, cutting is performed to obtain a cutting piece 9, and this cutting piece 9
Then, a ring body 12 having a predetermined diameter is formed so as to surround the circumference of the shaft (see FIG. 6) over the entire circumference. In particular, in this embodiment, as shown in FIG. Edge 9a, 9a
Are covered with a heat-shrinkable film 13 and bound. Even if the cut piece 9 is bound by the tape 11, when cut along a plane perpendicular to the axis, the fiber yarn is pulled out by the cutter at the time of cutting. Such fiber threads are cut pieces 9
If the end portions 9a, 9a are covered with the heat-shrinkable film 13, the generation of fiber pieces and abrasion powder can be prevented, although the sealability or the product will be adversely affected if the distance from the end is removed. Further, the heat-shrinkable film 13 can naturally prevent fraying at the end portions 9a, 9a.

In order to cover the end portions 9a, 9a with the heat-shrinkable film 13, as is well known, a cylindrical heat-shrinkable film 13 having a diameter larger than that of the cut piece 9 is prepared, and the end portions 9a, 9a are covered with the heat-shrinkable film 13. It may be heated from the outside with a dryer or the like. However, in this case, it is preferable to cover the temporarily fixed tape 11. This is to prevent the tape 11 from being peeled off or damaged and causing the same trouble as the friction powder.

As the heat-shrinkable film 13, for example, it is preferable to use a fluororesin tube, a vinyl chloride tube, a polypropylene tube, a polyethylene tube or the like, and particularly preferably, a fluororesin tube having excellent heat resistance and strength is used. Preferably.

By covering with the heat-shrinkable film 13 in this way, the heat-shrinkable film 13 covers the end portions 9a, 9a of the cutting pieces 9 considerably strongly, so that the binding becomes stronger and easy. It is possible to prevent fraying and the like, and when the shaft is sealed later by using the ring body 12 manufactured from the cut piece 9, thermal contraction is also caused by frictional force when slidingly contacting the rotating shaft and the like. The elastic film 13 itself does not peel off from the string-like body 10, and the fixed holding is ensured.

Further, the end portions 9a, 9a of the cut piece 9 are attached to the heat-shrinkable film 13
In the case of bundling with, it is preferable that a part of the heat-shrinkable film 13 is set in a state of protruding from the end portions 9a, 9a. By doing so, as shown in FIG. 5, the heat-shrinkable film 13 covers a part or the whole of the end faces 9b, 9b at the end portions 9a, 9a of the cut piece 9, and the fibers from the end faces 9b, 9b are covered. This makes it possible to almost completely prevent the thread from protruding and fraying.

After binding the ends 9a, 9a of the cut pieces 9 with the heat-shrinkable film 13, bend them into a ring shape so that both end surfaces 9b, 9b come into contact with each other, and put them in a mold for compression molding. Packing G is completed.

In order to seal the shaft using the gland packing G, a plurality of gland packings G are put in a stuffing box 2 or the like as shown in FIG. Good.

In the above-mentioned embodiment, the gland packing is formed by stacking a plurality of ring bodies, but the present invention is not limited to this, and the gland packing in which the packing material is spirally filled. It can also be applied to G. The gland packing G thus formed can correspond to the size of the stuffing box, and is not only versatile but also convenient during assembly work.

Further, the cutting piece 9 of the above embodiment is cut along a plane perpendicular to the axis of the shaft so as to have a length corresponding to the outer circumference of the shaft to be sealed, but the present invention is not limited to this. It goes without saying that the present invention can also be applied to the case of intersecting with the axis line at a predetermined angle instead of the above.

Effect of the Invention As described above, in the gland packing according to the present invention, the end of the cut piece obtained by cutting the string-like body is covered with the heat-shrinkable film. Even when sealing is performed, fraying at the end portion where the fiber yarns are braided is prevented, and there is no possibility that abrasion powder of the fiber yarns will be generated or that this will be mixed into the fluid to be sealed.

Further, by temporarily fixing the cut portion of the string-like body with a tape, it is possible to prevent fraying when cutting the string-like body or when covering one end of the cut piece with a heat-shrinkable film. By covering a part or the whole of the end surface of the cut piece end with the elastic film, the prevention of the fray and the like becomes almost complete.

[Brief description of drawings]

FIG. 1 is a perspective view showing a gland packing according to an embodiment of the present invention, and FIGS. 2 to 5 are working steps in the case of manufacturing the gland packing of the ring body by covering an end of a cut piece with a heat shrinkable film. FIG. 6 is a cross-sectional view showing the usage state of the gland packing, and FIG. 7 is a perspective view showing a conventional gland packing. 9 ... Cutting piece, 9a ... End, 9b ... End face 10 ... String-like body, G ... Gland packing 11 ... Tape, 13 ... Heat shrinkable film

Claims (3)

[Scope of utility model registration request] 1. A gland packing obtained by molding a cut piece obtained by cutting a long string-like body formed by braiding fiber yarns into a ring shape in which both end surfaces of the cut piece face each other. Gland packing made by covering the ends of the cut pieces with a heat-shrinkable film. 2. The gland packing according to claim 1, wherein the string-shaped body is temporarily fixed with a tape at the portion to be cut. 3. The gland packing according to claim 1 or 2, wherein the heat-shrinkable film covers a part or the whole of the end surface of the cut piece.