JPH0446119Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Field of Application) The present invention relates to a gland packing used in shaft seals of fluid machinery, and more particularly to a gland packing with improved bending followability during ring forming.

(Prior art) In the ground packkin, as shown in Fig. 3, a plurality of fibers are bundled to form a knitting yarn 10A, and this knitting yarn 10A is subjected to braiding methods such as eight-knitting, lattice knitting, and bag-knitting. Braid body 1 twisted and braided into a string shape
0, a central core 20A disposed along the longitudinal direction of the axial center of the braided body 10, and an outer core 20B disposed along the longitudinal direction at the corner of the braided body 10.
A core material 20 is known.

The gland packing is cut into a predetermined length, then formed into a ring, and is housed in a stuff-in box while being fitted onto the sealing shaft.

(Problems to be Solved by the Invention) By the way, if the gland packing is bent during the above-mentioned ring forming or when being wound around the drum of a continuous molding machine, for example, the neutral position of the gland packing as shown in Fig. 4 may occur. A tensile force acts on the radially outer side of the surface C, causing elongation, and a compressive force acts on the radially inner side, causing contraction.

The braided body 10 constituting the ground packing has a structure in which the knitting yarn 10A, which is a bundle of multiple fibers, is braided, so it is highly elastic and has the property of effectively absorbing the aforementioned expansion and contraction, that is, it has excellent bending tracking. It has characteristics.

However, since the core material 20 is made of non-stretchable long fibers arranged in a straight manner, it cannot effectively absorb the aforementioned expansion and contraction. Therefore, when forming the ring,
Outer core 20B located on the inside diameter where the amount of shrinkage is large
This causes a problem in that the outer core 20B protrudes from the end face of the cut, and the outer core 20B, which is disposed on the radially outer side where there is a large amount of elongation, retracts from the end face of the cut.

Although the core material 20 made of natural fibers such as asbestos, cotton, and hemp has relatively good elasticity, the core material 20 has been increasingly used in recent years, that is, synthetic resin long fibers called filaments. or,
The core material 20, which is made of long fibers obtained by cutting a synthetic resin tape material called a tape into pieces in the longitudinal direction, has poor elasticity and poor bending conformability, so it cannot be used as described above. The occurrence of defects becomes more noticeable.

If such a problem occurs, poor adhesion of the cut surface during ring molding and especially the braided body 10.
A problem arises in that a bump-like protuberance occurs on the radially inner side of the gland, deteriorating the shaft sealing properties of the gland packing.

The present invention was made to solve these problems, and although the braided body and core material are ground packing made of fibers other than asbestos fibers, the core material has high elasticity and is easy to use during ring forming. An object of the present invention is to provide a gland packing that has improved bending followability and can ensure suitable shaft sealing characteristics.

(Means for Solving the Problems) The ground packkin according to the present invention includes a braided body in which a plurality of fibers are bundled into a knitting yarn, a plurality of the knitted yarns are braided into a square string shape, and this braided body. and a core material consisting of a core arranged along the longitudinal direction at the axial center portion of the braided body and an outer core arranged along the longitudinal direction at the corner portion of the braided body, and the braided body and the core material are In the ground packing made of fibers other than asbestos fibers, the braided body is formed of long fibers, and at least the outer core of the core material is formed of spun yarn.

(Function) In the present invention, by forming at least the outer core of the core material from highly elastic spun yarn, the bending followability of the core material is improved, and the outer core of the core material is particularly short. Since it is a spun yarn made of fibers, the intertwining with the fibers of the braided body increases, resulting in an increase in the coefficient of friction and effectively preventing protrusion of the core material.

(Embodiment) Fig. 1 is a partially cutaway perspective view showing an embodiment of the present invention. It is formed by braiding a plurality of threads 1A into a string shape using, for example, lattice knitting, and forming the threads into a rectangular cross section.

The plurality of fibers forming the knitting yarn 1A include one or more types of long fibers such as aromatic polyamide fibers, phenol resin fibers, fluororesin fibers, glass fibers, carbon fibers, and metal fibers. These fibers are appropriately selected and used. Then, plugging materials (not shown) such as fluororesin dispersion, silicone oil, and graphite powder are impregnated and fixed.

Reference numeral 2 indicates a core material, and in this embodiment, one core material 2A is arranged along the longitudinal direction of the axial core part of the braided body 1.
and four outer cores 2B arranged along the longitudinal direction at the four corners of a rectangular cross section, and these core materials 2 are made of, for example, aromatic polyamide fibers, phenolic resin fibers, fluororesin fibers, glass fibers, etc. , spun yarn made from short fibers such as carbon fibers and metal fibers, and can be appropriately selected from among these.

In this example, aromatic polyamide long fibers are used as the knitting yarn 1A, and the core material 2
Aromatic polyamide spun yarn is used as the material.

The gland packing having the above structure is cut to a predetermined length, then formed into a ring as shown in Fig. 2, and is used by being fitted onto a sealing shaft (not shown) and stored in a stuff-in box. Ru.

By molding the ground packing into a ring,
A tensile force acts on the radially outer side of the neutral plane C, causing elongation, and a compressive force acts on the radially inner side, causing shrinkage. Because of its structure, it is highly elastic and has excellent bending follow-up properties, so it can effectively absorb the expansion and contraction described above, so that unnatural distortion does not occur.

On the other hand, a tensile force acts on each of the two outer cores 2B disposed at the upper corner of the core material 2,
In addition, the two outer cores 2B located at the lower corners
A compressive force acts on each of these outer cores 2
B is made of a spun yarn that is highly stretchable and has excellent bending following properties, and the outer core 2B made of the spun yarn increases entanglement with the fibers of the braided body 1 to increase the coefficient of friction. As a result, as with conventional gland packing, there is a problem in which the outer core 2B, which is placed on the radially inner side where there is a large amount of shrinkage, that is, on the lower corner, protrudes from the end face of the cut, and on the radially outer side where there is a large amount of elongation, i.e. Outer core 2 located at the upper corner
It is possible to effectively prevent a problem in which B is sunk in from the end face of the cut.

On the other hand, although tensile force acts on the inner core 2A on its radially outer side and compressive force acts on its radially inner side, they are effectively absorbed for the same reason as described above.

Therefore, poor adhesion of cut surfaces, bump-like protrusions, unnatural distortion, etc. occurring on the surface of the braided body 1 during ring forming are prevented, and rings can be formed with uniform inner and outer curvatures. Therefore, the conformability to the outer circumferential surface of the sealing shaft and the inner circumferential surface of the tusf-in box is improved, and the shaft sealing characteristics are improved.

In the embodiment described above, the core 2A and the outer core 2B constituting the core material 2 are each made of spun yarn, but the present invention is not limited to the embodiment described above. The inner core 2A, which is arranged along the neutral plane C of the outer core 2B and therefore has a smaller amount of expansion and contraction than the outer core 2B, may be formed of a core material made of long fibers, for example, instead of the spun yarn. That is, a relatively small amount of expansion and contraction in the vicinity of the neutral plane C can be practically absorbed.

(Effects of the invention) As explained above, according to the invention, in a ground packing whose braided body and core material are made of fibers other than asbestos fibers, at least the outer core of the core material is formed of spun yarn. This improves the bending followability during ring forming, and increases the intertwining with the fibers of the braided body, increasing the coefficient of friction.
Protrusion of the core material is effectively prevented.

Therefore, even if the braided body is constructed from filament yarns and tapes, which have been increasingly used in recent years, suitable shaft sealing properties can be ensured by constructing the inner outer core of at least spun yarn.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway perspective view showing an embodiment of the gland packing according to the present invention, Fig. 2 is an explanatory front view during ring forming, and Fig. 3 is a partially cutaway perspective view of a conventional example. FIG. 4 is a front view showing a state in the middle of ring molding. 1... Braided body, 1A... Knitting yarn, 2... Core material,
2A...Central core, 2B...Outer core.

Claims (1)

[Scope of utility model registration request] A braided body in which a plurality of fibers are bundled to form a knitting yarn, and a plurality of the knitted yarns are braided into a square string shape, a core disposed along the longitudinal direction at the core of the braided body, and the braided body. In the ground packaging, which has a core material consisting of an outer core arranged along the longitudinal direction at the corner of the body, and the braided body and the core material are made of fibers other than asbestos fiber, the braided body is 1. A ground packing, characterized in that it is made of fiber, and at least the outer core of the core material is made of spun yarn.