JP2530534B2 - Packing and its manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packing suitable for shaft sealing of fluid devices such as valves and pumps, and more particularly to a packing formed by using a flexible graphite sheet and an improvement in its manufacturing method. .

[0002]

2. Description of the Related Art Conventionally, as a packing for a shaft seal of this type,
Multiple flexible graphite sheets cut to a width of 5 mm or less are stacked, and the surface is knit-knitted with fibers or bag-knitted to form a knitting yarn, and the knitting yarns are bundled and twisted or braided. Gland packing formed by
It is disclosed in Japanese Patent Laid-Open No. 3-1863. The packing has the following effects due to its structure.

1) By using a flexible graphite sheet cut to a width of 5 mm or less, the compressibility and the allowable number of twists are dramatically increased. 2) By stacking a plurality of the sheets, the tensile strength is increased and the toughness is significantly improved. 3) Therefore, it is possible to easily and surely form the string-like body by covering the plurality of sheets with a fiber material.

[0004]

However, the above-mentioned gland packing has the following drawbacks. 1) When a plurality of superposed graphite sheets are covered with a fibrous material, if the sheets are bent or the like due to the low friction property peculiar to graphite, the sheets tend to be misaligned in the longitudinal direction. This part of the swelling rises like a hump to form a protrusion called a knot, and the braided body using this as a knitting yarn is likely to deteriorate the sealing property. 2) Since the graphite sheets made by stacking multiple sheets have increased rigidity, the so-called bending radius becomes large, and the braided body using this as a knitting thread also becomes rigid, and (1) the flexibility decreases and the stuffing box is loaded. Will be difficult. (2) The compressibility is reduced, and the conformability to the shaft is reduced. (3) Larger stuffing box structure (necessary to increase bolt strength) due to increased tightening pressure required for sealing and increased frictional force with the shaft, and when used for automatic valves, etc. Actuator (drive device)
Need to be larger. (4) Due to the stress hardening of the packing after use, the sticking of the packing tool deteriorates and the packing removal time becomes long. (5) 5 mm because the flexible graphite sheet has extremely low toughness
The production yield of cut sheets having a width equal to or smaller than the width is low. Therefore, the product cost becomes high.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in order to completely eliminate the drawbacks of the conventional gland packing which uses a knitting yarn formed by bag-knitting or knitting a flexible graphite sheet with a fiber material. In particular, the knitting yarn with the above configuration can be used independently as a packing material. Furthermore, as a gland packing, it has appropriate flexibility and compressibility, which improves the loadability of the stuffing box and reduces the tightening. An object of the present invention is to provide a packing which has good conformability to pressure and sealability, and also has good workability in taking out with a packing tool after use.

[0006]

The packing material according to the first invention of the present application includes a flexible graphite sheet single layer having a width of 6 mm or more, and a knitted bag body made of a fiber material coated on the graphite sheet. By stretching in the longitudinal direction, the knitted bag body extends in the length direction, shrinks in the width direction and is narrowed down,
Or in the width direction to follow the change in shape of the graphite sheet is woven bag
The gist of the invention is that it is indented and plastically deformed into a curl shape, and both widthwise edges thereof are projected in a sawtooth shape from the stitches of the knitting bag body. A method for manufacturing a packing material according to the second invention of the present application comprises a step of knitting a flexible graphite sheet single layer having a width of 6 mm or more in a bag shape by knitting and covering the flexible graphite sheet single layer to form a knitted bag body, and knitting with the graphite sheet. a bag together stretched in the longitudinal direction, the length direction of the knitting bag by its stretching
Stretches and narrows down so that it shrinks in the width direction, and the graphite sheet is rolled into the width direction following the shape change of the knitted bag body.
The present invention is characterized in that it comprises a stretching step of plastically deforming in a curl shape and projecting both widthwise edges thereof in a sawtooth shape from the stitches of the knitting bag body. The packing according to the third invention of the present application is characterized in that a single layer of a flexible graphite sheet having a width of 6 mm or more and a knitting bag body made of a fibrous material with which the graphite sheet is covered are stretched together in the longitudinal direction so that the knitting is performed. The bag body extends in the length direction, shrinks in the width direction and is narrowed down, and the graphite sheet is plastically deformed into a curl shape by being rolled in the width direction following the shape change of the knitted bag body .
A knitting yarn is used in which both widthwise edges are projected in a sawtooth shape from the stitches of a knitting bag, and a plurality of these knitting yarns are braided or twisted into a cord without a core or with a core. The point is that they are processed. A method for manufacturing a packing according to a fourth aspect of the present invention comprises a step of knitting a flexible graphite sheet single layer having a width of 6 mm or more with a fiber material in a bag shape to form a knitted bag body, and the graphite sheet and the knitted bag. the body together stretched in the longitudinal direction, the length of the knitting bag by its stretching
The graphite sheet is narrowed so that it extends in the width direction and contracts in the width direction, and the graphite sheet is rounded in the width direction following the shape change of the knitted bag body.
While being plastically deformed into a curl shape so as to be squeezed, both widthwise edges of the knitting bag are made to project in a sawtooth shape to form a knitting yarn, and a plurality of the radiant yarns are provided without a core Alternatively, the gist of the present invention is that it comprises a step of twisting or twisting into a cord with a core.

[0007]

The knitting yarn having the above-described structure has its flexibility increased by plastic deformation of the graphite sheet due to stretching, and a part of the graphite sheet protrudes from the stitches of the knitting bag body in a sawtooth shape. The sheet and the knitting bag are firmly bonded. Further, in the braided packing that is braided or twisted into a string with the knitting yarn, the sawtooth-like protruding portion projecting from the stitch of the knitting bag body has a tensile force acting on the knitting yarn during braiding or twisting or The twisting force plastically deforms like a scale, and the inside and outside of the fiber are almost completely covered with graphite.

[0008]

EXAMPLE FIG. 1 (a), (b), (c), (d),
(E) and (f) show the manufacturing process of the braided packing of the present invention. In FIG. 1 (a), A is a knitting yarn that forms a packing material for shaft sealing, 1 is a flexible graphite tape, and 2 is a knitted bag body in which a graphite tape is woven and covered with a fiber material in a bag shape. . The graphite tape 1 is a single-layer sheet cut into a width of 6 mm or more and folded back so that both ends in the width direction are 1 mm or more so as not to overlap each other, and 1a is a folded portion. The presence of this folded-back portion causes a laminating action, and has an effect of enhancing tensile strength and toughness. However, as shown in FIG. 2, a knitting yarn using a graphite tape having no folded portion may be used.

FIG. 1 (b) is a plan view showing a state in which the knitting yarn A is stretched together with the graphite tape 1 and the knitting bag body 2 by applying a tensile force in the longitudinal direction thereof, and FIG. 1 (c) is a partial view. An enlarged plan view, FIG. 1D is a sectional view taken along the line (XX). Stretching tension is 1-6kgf and knitting yarn elongation is 8-1
2%, preferably 10-11 elongation with a tensile force of 2-3 kgf
%. Graphite tape with a knitting bag that stretches 8 to 12% under a tensile force of less than 1 kgf cannot be used for knitting yarn because it will break when it is applied to a normal braider. In addition, in the graphite tape with a knitting bag that stretches by 8 to 12% after the tensile force exceeds 6 kgf, the graphite tape in the knitting bag will rupture when a tensile force is applied, and only the portion of the knitting bag will be generated, resulting in sealing performance. The pulling force is appropriate in the above-mentioned range because it causes a large decrease.

[0010] The graphite is formed on the Symbol knitting yarn only A tape 1
Together with the woven bag 2 when stretched in the longitudinal direction, knitting bag
2 extends in the longitudinal direction, Ru narrowed narrower in the width direction shrinks in the width direction. At that time, even if the graphite sheet is stretched, it almost elongates.
Since it does not exist, it follows the shape change of the narrowly knitted bag body.
Then, it is rolled in the width direction and plastically deformed into a curl,
In addition, the widthwise edge of the graphite tape protrudes from the stitches of the knitting bag body 2 in a sawtooth shape. Reference numeral 1b denotes a saw-toothed protrusion. By forming the protrusion 1b, the graphite tape and the knitting bag are firmly bonded and the flexibility of the knitting yarn itself is increased. As a method of drawing the knitting yarn A, a method of drawing the knitting yarn A through a drive feed roll, which is separately provided on the way, when the graphite tape is bag-covered with fibers by a normal knitting machine and then wound on a bobbin, is applied. However, it is not limited to this method.

FIG. 1 (e) shows a gland packing 3 braided in a string shape using a plurality of knitting yarns A having the above construction. During this braiding, the graphite sawtooth protrusions 1b protruding from the stitches of the knitting bag body 2 are plastically deformed in a scale shape by the tensile force and the twisting force acting on the knitting yarn during the braiding, and the inside and outside of the fiber are scale-shaped. Almost completely covered with graphite. FIG.
In (f), the scale-like graphite portion on the packing surface is indicated by reference numeral 1c.
Indicated by

FIG. 3 shows a gland packing 4 in which a plurality of knitting yarns A having the above-mentioned structure are bundled and formed into a string shape by twisting.

In FIG. 4, a flexible graphite powder, a kneaded product obtained by adding graphite to a graphite powder and a rubber material, and a kneaded product obtained by extrusion are formed into a rod shape, and the rod-shaped material 5 is used as a core to form a knitting yarn with the knitting yarn A having the above-mentioned configuration. The covered cord-shaped gland packing 6 is shown.

Next, specific examples of the present invention will be shown below. Example (1) With nominal dimensions, width 7.0 mm, thickness 0.381 mm (± 0.00
5 mm), a density ^{1.144g / cm 3 (± 0.043g /} cm 3),
Flexible graphite (trade name "GRAFOIL") manufactured by Union Carbide Corporation of the United States with an actual mass of 2.9 g per 1 m length
Tape as a single layer, send it to a bag knitting machine, and use a commercially available wire diameter of 0.1 mm and SUS316 metal wire on the surface.
Take one knitting yarn, handle speed 135r.pm, number of gears 40, lower 50, weight 22.5g, and sew 16 knitting bags with both ends in the sheet width direction folded back about 1mm at intervals of about 5mm. A knitting yarn having a mass of 4.4 g per 1 m length was obtained. The above-mentioned knitting yarn sent out from the bag knitting machine was drawn by a feed drive roller with a pulling force of 3 kgf. By the stretching, the knitted bag body is narrowed down, the graphite tape is plastically deformed in a curl shape in the width direction, and both edges in the width direction are saw-toothed at a pitch of 1 mm or more from the stitch of the knitted bag body (about 2 mm on one side). To form a knitting yarn in which the graphite tape and the metal wire are joined by the protruding portion.
The number of gears, upper and lower gears 40, 40, and 640 g of weight were struck in 8 corners.

Then, the above-mentioned 8-beat square knitted body was 16-stroke circularly knitted with 16 knitting yarns, the number of gears was 40 upper and 70 lower, and 600 g of weight. After that, the circular knitted body is made to have a weight ratio of rubber: graphite:
It was dipped in a mixed solution of toluene = 6: 94: 150 for several seconds and then air-dried for 24 hours to volatilize the solvent. Next, the air-dried string-like braid is rolled on four points, and the length is 9.5 m.
A cord-shaped gland packing having a square cross section with m, width of 9.5 mm, and density of 1.3 g / cm ³ was obtained.

Example (2) Flexible graphite by weight%: graphite: rubber: toluene = 70: 2
The kneaded product of 0:10:19 was put into a commercially available screw type extruder and extruded at a ratio of the cross-sectional area of the charging portion to the cross-sectional area of the nozzle portion of 150: 1 and the nozzle diameter of 7.4 mm. Air-dried as described above to obtain a rod-shaped material having a thickness of 7.3 mm and a density of 0.7 g / cm ³ .

Next, the outer circumference of the rod-shaped material is provided with 16 knitting yarns of Example (1), 40 gears, 40 gears, and 450 weights.
16 round crocheting was performed with g, and this circularly woven body was dipped in a mixed solution of rubber: graphite: toluene = 6: 94: 150 at a weight% for several seconds and then air-dried for 24 hours or more to volatilize the solvent. Roll the four points of the air-dried string-like braid, and roll vertically for 9.5
Thus, a string-shaped gland packing having a square cross section with an area of 0.1 mm, a width of 9.5 mm and a density of 1.1 g / cm ³ was obtained.

The packing of the present invention according to the above embodiments (1) and (2), and the conventional packing (P / # 6711, vertical size 9.5 mm, horizontal 9.5 m) manufactured by Nippon Pillar Industry Co., Ltd.
m) was used as a specimen, and this type of packing was tested under the conditions described below.

Test method (1) Each of the above-mentioned sample packings was set on two support bases having a span of 100 mm, and the packing part at the midpoint of the span (50 mm) was pulled with a force of 1 kg by a spring measure. The amount of bending was measured. Table 1 shows the results.

[0020]

[Table 1]

(2) Each sample packing has an inner diameter of 50.1
mm with an outer diameter of 69.9 mm is used to form a ring with a surface pressure of 300 kgf / cm ² and the molded body has an inner diameter of 50.0 mm and an outer diameter of 70.0.
1 ring was loaded into a mm die and it was pressed with a 20tonf press to 10
It was compressed at a speed of tonf / 5 min, and the compression ratio was measured by the following formula (1). The results are shown in Table 2.

[0022]

[Table 2]

(3) Each sample packing has an inner diameter of 50.1
mm with an outer diameter of 69.9 mm is used to form a ring with a surface pressure of 300 kgf / cm ² and the molded body has an inner diameter of 50.0 mm and an outer diameter of 70.0.
Load 6 rings into mm valve stuffing box,
Next, after inserting a lantern ring for leak detection, another two rings were loaded. Next, apply the packing to a surface pressure of 300 kgf / cm.
^After tightening at ² , steam of 250 kgf / cm ² at 600 ° C. was introduced into the valve. In this case, use a heater on the outer wall of the stuffing box to prevent the temperature of the gland from decreasing by 600 ° C.
It was heated to. In this state, the steam is continuously aerated for 48 hours, and once every 8 hours, the stroke is 200 mm and the speed is 7
The valve was opened and closed 20 times at 00 mm / min, the sealing performance was measured from the amount of steam leakage during this time, the packing height and the axial load were measured,
Measure the frictional force by the following formula (2), stop ventilation and cool the valve to room temperature, measure the packing tightening force, stop ventilation and cool the valve to room temperature, measure the packing tightening force,
After measuring the stress relaxation rate by the following formula (3), each packing was taken out by a commercially available packing tool, the time required at that time was measured, and the heat loss of the packing was measured. Table 3 shows the results.

[0024]

[Table 3]

[0025]

According to the present invention, the following effects can be obtained. (1) A knitting yarn obtained by knitting a graphite sheet into a bag shape by covering it in a bag shape and then stretching it has remarkably higher flexibility than a conventional knitting yarn, and the graphite sheet is a part of the knitting bag. As it has a structure that is connected to the body, it can be used by itself as a tadpole packing (aircraft McLar seal, door packing), seal tape, electromagnetic wave shield material, antistatic material,
When used as a gasket material, the following effects can be obtained. When used for tadpole packing: (a) remarkably good sealability, (b) remarkably good slippage, (c) inexpensive and versatile, (d) good heat resistance,
(E) Durable and long life, (f) Safety and hygiene,
No odor when used. When used as a sealing tape: (a) Good sealing property, (b) Good heat resistance, (c) Good durability, (d) Safety and hygiene. When used as an electromagnetic wave shield material: (a) good electromagnetic wave shield and antistatic property, (b) good heat resistance, (c) good durability, (d) inexpensive.
(E) Good setability, (f) Safety and hygiene. When used as an antistatic material: (a) Can be completely prevented, (b) Good heat resistance, (c)
Good durability, (d) inexpensive, (e) good setability, (f) safety and hygiene. When used as a gasket material: (a) Good sealability, (b) Good heat resistance, (c) Small stress relaxation rate, (d) Large compression elasticity, (e) Good durability, (f) ) Hardening after use is small and it does not stick to the (g) flange, so it is easy to remove.

(2) In the production of the knitting yarn, a width of 6 mm
Since the above-mentioned flexible graphite has a large absolute value of tensile strength even in a single layer, it can be fed into the fiber coating step without being cut. (3) Since the graphite sheet is a single layer, there is no deviation in the longitudinal direction of the sheet, and no nodules are formed due to the fiber coating. Therefore, the uniformity of the density of the knitting yarn is improved. Further, the sealing property of the braided body (or the twisted string-like body) made of the knitting yarn is improved. (4) When a graphite sheet having both ends folded back is used, the toughness of the sheet is improved because the torsional strength of the entire graphite sheet increases due to the laminated action of the folded back portions.

(5) The graphite sheet is a single layer and has low rigidity, and the graphite sheet is plastically deformed by stretching after the covering of the knitting bag body, and a part of the graphite sheet is integrated with the fiber and protrudes outside the stitch. As described above, the knitting yarn that is formed has increased flexibility, so the braid (or twisted string) using this knitting yarn is flexible and can be loaded into a stuffing box or the like. Is improved and the compression ratio is increased, so that the axial conformability is improved. Furthermore, the graphite sheet and fibers are well integrated inside the braid (or the twisted string-like body), and the graphite sheet is exposed on the outside (surface portion) in a scale-like shape. The plastic sheet is plastically deformed to fill the voids, which improves the sealing performance.When the valve is opened and closed, the low friction coefficient of graphite reduces the packing friction force, which reduces the size of the stuffing box and actuator. Can be realized. Furthermore, since the graphite sheet has a scale-like shape, the sticking-out of the packing removal tool is extremely improved, so that the packing removal workability after use is significantly improved. (6) Since a flexible graphite sheet with a good yield (sheet with a width of 6 mm or more) is used and can be manufactured by a simple process, the product cost can be reduced. (7) Even in a gland packing formed by bag-knitting an extruded product composed of flexible graphite particles, rubber and graphite with the knitting yarn, the extruded product can be produced inexpensively and easily in a large amount by an ordinary method. It can be produced, and the versatility can be greatly improved.

[Brief description of drawings]

FIG. 1 is a packing manufacturing process diagram showing an embodiment of the present invention, in which (a) is a perspective view of a knitting yarn before drawing, (b) is a plan view of the knitting yarn after drawing, and (c) is a partial view. Enlarged plan view, (d)
Is a cross-sectional view taken along line X-X, (e) is a perspective view of a braided packing using a knitting yarn, and (f) is an enlarged view of a surface portion thereof.

FIG. 2 is a perspective view of a knitting yarn before stretching showing another embodiment of the present invention.

FIG. 3 is a perspective view of a packing formed by twisting a knitting yarn.

FIG. 4 is a perspective view of a braided packing showing another embodiment of the present invention.

[Explanation of symbols]

 A knitting yarn 1 flexible graphite tape 2 knitting bag body 1a folded portion 1b protruding portion due to plastic deformation of graphite tape 3, 4, 6 packing

Claims (4)

(57) [Claims] 1. A flexible graphite sheet single layer having a width of 6 mm or more and a knitted bag body made of a fibrous material coated on the graphite sheet are stretched together in the longitudinal direction, whereby the length of the knitted bag body is increased. Direction, shrinks in the width direction and is narrowed down,
Or in the width direction to follow the change in shape of the graphite sheet is woven bag
A packing material characterized in that it is curled into a curled shape and both edges in the width direction thereof are projected in a sawtooth shape from the stitches of the knitting bag body. 2. A step of knitting and covering a single layer of a flexible graphite sheet having a width of 6 mm or more with a fibrous material in a bag shape to form a knitted bag body, and stretching both the graphite sheet and the thin bag body in the longitudinal direction. Then, by stretching the knitted bag body in the longitudinal direction,
Narrow the bag so that it shrinks in the width direction, and woven a graphite sheet into a bag.
A stretching process in which the edges of the width direction are plastically deformed so that they are curled in the width direction following the change in the shape of the body, and both edges in the width direction are projected in a sawtooth shape from the stitches of the knitted bag body. A packing material manufacturing method characterized by being made. 3. A flexible graphite sheet single layer having a width of 6 mm or more and a knitted bag body made of a fibrous material coated on the graphite sheet are stretched together in the longitudinal direction to obtain a knitted bag body having a length. Direction, shrinks in the width direction and is narrowed down,
Or in the width direction to follow the change in shape of the graphite sheet is woven bag
The knitting yarn is made by being entangled and plastically deformed into a curl shape, and its widthwise both edges are projected in a sawtooth shape from the stitches of the knitting bag body. A packing characterized by being braided or twisted into a string with a core or a core. 4. A step of knitting and covering a single layer of a flexible graphite sheet having a width of 6 mm or more with a fiber material in a bag shape to form a knitted bag body, and stretching both the graphite sheet and the knitted bag body in the longitudinal direction. Then, by stretching the knitted bag body in the longitudinal direction,
Narrow the bag so that it shrinks in the width direction, and woven a graphite sheet into a bag.
Following the shape change of the body, it is plastically deformed into a curl shape so that it is rolled in the width direction, and both edges in the width direction are protruded from the stitches of the knitting bag body in a sawtooth shape to form a knitting yarn. And a step of braiding or twisting the plurality of knitting yarns without a core or with a core into a cord shape.