JP2530533B2 - Mold packing and manufacturing method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold packing made of flexible graphite used for a shaft sealing portion of a fluid device such as a valve or a pump, and an improvement in its manufacturing method.

[0002]

2. Description of the Related Art Conventionally, as a gland packing used for a shaft sealing portion (stuffing box) of a fluid device, a mold packing using a flexible graphite substrate is known. The flexible graphite retains the heat resistance, chemical resistance, lubrication, thermal conductivity, etc. of graphite as it is, and also has special properties such as flexibility and elasticity that cannot be expected from conventional graphite. However, there are some points that it is easy to collapse, so there is a drawback that it requires careful handling when loading into the stuffing box, and that it is difficult to take it out from the stuffing box, which is troublesome.

In order to solve the above problems, a flexible graphite tape is overlaid with a metal net having a width narrower than that of the tape, and the metal net is pressed onto the flexible graphite tape with a press or a roll. Make a composite tape material, wrap this composite tape material around a core rod in a spiral shape, and in this state, compress it in the thickness direction and width direction with a molding die,
A ring-shaped mold packing has been proposed.

According to the above construction, the flexible graphite packing can be made hard to collapse due to the reinforcement of the metal net, and the metal net can be used as a hooking member of the packing take-out tool, so that the packing take-out workability can be improved. .

[0005]

However, a mold packing which is manufactured by crimping a metal net on a flexible graphite tape to form a composite tape material, winding the composite tape material, and compressing it with a molding die is used. , there are the following problems.

(A) Laying a metal mesh on the flexible graphite tape: (1) The work becomes complicated. (2) It is difficult to center the tape and the metal net. (3) Mass production is difficult. (4) The flexible graphite tape itself is easy to cut during handling. (5) If the centering is insufficient, the metal net is exposed on the surface of the product at the time of final product, and microscopic gaps are generated, which deteriorates the sealing property.

(B) Pressing a metal net onto the tape with a press or roll: (1) Work is complicated. (2) It is necessary to prevent the centering between the tape and the metal mesh from being displaced. (3) Mass production is difficult. (4) By pressing or rolling, the tape becomes hard and the flexibility becomes poor. (5) When the centering is misaligned, the metal net is exposed on the surface of the final product as in the above case, and microscopic gaps are formed, resulting in deterioration of the sealing property.

(C) Wrapping the composite tape material with metal mesh around the core rod: (1) The tape is hard and the workability is poor. (2) Therefore, the work becomes complicated. (3) Mass production is difficult. (4) When winding, it is necessary to wind the flexible graphite single tape around the inner diameter side and the outer diameter side. In the case of a metal net, there is a risk of damaging the shaft at the exposed parts on the product surface, which is prevented with a simple graphite tape.

(D) Compression-molding with a molding die: (1) The tape is hard, so plastic deformation is difficult. Therefore, a gap is likely to be formed between the graphite portion and the metal net.

(E) Product after compression molding: (1) Density (ρ) = 1.5 to 1.7 g / cm ³ (in the case of metal mesh) (2) Small compression rate. 300kgf / cm ² Approx. 1 when tightened
0%. (3) The sealing property is inferior to the product without the metal mesh. (4) It is expensive. Poor versatility. (5) When taking out the packing, the cutting edge of the take-out tool does not bite well.

[0011]

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of a mold packing using a composite tape material obtained by stacking and compressing a flexible graphite tape with a mesh member such as a metal mesh. In addition, the characteristics of flexible graphite are fully utilized, and the stuffing box can be loaded easily and the packing tool after use can be taken out easily.
It is an object of the present invention to provide a mold packing that has good conformability and sealability at a low tightening pressure.

[0012]

A mold packing 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 thin bag 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, and the graphite sheet is curled in the width direction following the shape change of the knitted bag body. Is plastically deformed to
The gist of the present invention is that a band-shaped material whose both edges in the width direction are projected in a saw-tooth shape from the stitches of the knitted bag body is used as a mold material, and the mold material is compression molded in a spiral state. A method for manufacturing a mold packing according to the second invention of the present application is the step of weaving 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 radiating bag, and the graphite sheet. Stretching together with the knitting bag body in the longitudinal direction, and stretching the knitting bag body in the length direction,
Knit a graphite sheet by narrowing it down so that it shrinks in the width direction.
As the shape of the bag changes, it can be rolled in the width direction
And the plastic material is curled into a curl shape, and both edges in the width direction thereof are made to protrude from the stitches of the knitting bag body in a sawtooth shape to form a mold material, and the mold material is formed into a spiral shape.
It is the gist that it comprises a step of putting in a molding frame and compression-molding in a ring shape.

[0013]

In the mold material, the flexible graphite sheet has increased flexibility due to plastic deformation due to stretching, and the sheet is made into micro pieces, so that the deformability by external force is increased, Moreover, the flexible graphite sheet is in a state of being integrally connected to the knitting bag body by the protruding portion protruding from the stitch in a sawtooth shape. Therefore, the mold material
By forming a spiral shape and putting it in a molding die and compression-molding it, a ring-shaped mold packing having good flexibility, compressibility, and axial conformability and reinforced with a knitting bag can be obtained.

[0014]

EXAMPLE FIG. 1 (a), (b), (c), (d),
(E) and (f) show the manufacturing process of the mold packing of the present invention. In FIG. 1 (a), A is a mold material, 1 is a flexible graphite tape, and 2 is a knitted bag body in which a graphite tape is woven and covered in a bag shape with a fiber material. 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 and do not overlap each other.
Reference numeral 1a is the 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 molding material using a graphite tape having no folded portion may be used.

FIG. 1 (b) shows that the mold material A is pulled in the longitudinal direction together with the graphite tape 1 and the knitted bag body 2.
A plan view showing a stretched state, FIG. 1C is a partially enlarged plan view thereof, and FIG. 1D is a sectional view taken along line XX thereof.
Stretching tension is 1-6kgf and knitting yarn elongation is 8-12
%, Preferably 10 to 11% elongation with a tensile force of 2 to 3 kgf
Is. Graphite tape with a knitting bag that stretches 8 to 12% under a tensile force of less than 1 kgf is not preferable because it breaks when it is applied to an ordinary braider. Also, the tensile force is 6 kg
With a graphite tape with a knitted bag body that extends 8 to 12% after exceeding f, the graphite tape in the knitted bag body breaks when a tensile force is applied, and only the knitted bag body part is produced. Appropriate.

[0016] When stretched together with the upper liver Rudo material A was formed and graphite tape 1 and the woven bag body 2 in the longitudinal direction, woven bag body 2 extends in the longitudinal direction, narrowed narrower in the width direction shrinks in the width direction Re that. At that time, the graphite tape 1 was almost pulled
Since it does not stretch, the shape of the knitted bag body that has been narrowed down changes
Follow and are rounded in the width direction to be plastically deformed curled, and projecting serrated out from the width direction edges of the woven bag 2 stitches graphite tape. 1b is a saw-tooth protrusion. As a method of stretching the mold material A, when the graphite tape is woven into a bag shape by a conventional knitting machine and covered with a fiber material and wound on a bobbin, the mold material A is stretched through a drive feed roll provided separately in the middle thereof. The method applies, but is not limited to this method.

By stretching the mold material A, the flexibility of the flexible graphite sheet is increased by plastic deformation, and since the sheet is made into micro pieces, the deformability due to an external force is increased. In addition, the flexible graphite sheet is in a state of being integrally connected to the knitting bag body by the protruding portion 1b protruding from the stitch in a sawtooth shape.

FIG. 1 (e) shows a state in which an assembly of stretched mold materials A is compression-molded by a molding die, 3 is a lower die, 4 is an upper die, 5 is an inner die, and 6 is External type,
A ring-shaped mold packing 7 shown in FIG. 1 (f) is obtained by winding and setting the mold material A around the inner mold 5 in a spiral shape and compressing it.

Next, specific examples of the present invention will be described. Example (1) With nominal dimensions, width 20 mm, thickness 0.381 mm, and density 1.14
A single layer of 4 g / cm ³ flexible graphite (trade name “GRAFOIL”) tape made by Union Carbide of the United States was sent to the bag knitting machine, and the surface was commercialized with a wire diameter of 0.1 mm and SUS316 metal wire. Take one knitting yarn, handle speed 135r.p.
m, number of gears 40, lower 50, weight 22.5 g, both ends in the sheet width direction are folded back by about 1 mm with a pitch of about 5 mm, and a 16-punch bag knitted cover is made and sent out from the bag knitting machine. The coated body was stretched by a feed drive roller with a pulling force of 3 kgf. By this 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 arranged at a pitch of about 1 mm from the stitches (about 2 mm on one side) of the knitted bag body. A mold material was obtained in which the graphite tape and the metal wire were projected in a sawtooth shape, and the graphite tape and the metal wire were bonded by the sawtooth projection. This mold material was continuously wound on a bobbin.

Separately, the nominal size is 20 mm in width and 0.38 in thickness.
A single layer of flexible graphite tape made by the same company having a density of 1 mm and a density of 1.144 g / cm ³ was sent to a bag knitting machine, and the surface was made by Toho Rayon Co., Ltd. carbon fiber (trade name "Best Fight", thickness 7 μm
Take a knitting yarn, handle speed 135r.pm, gear up 40, down 5
0, weight 22.5 g, both ends in the sheet width direction are folded back by about 1 mm at a pitch of about 5 mm to make a 16-punch bag knitted covering body, and the covering body sent out from the bag knitting machine is driven by a driving roller. It was stretched with a pulling force of 3 kgf. By this 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 arranged at a pitch of about 1 mm from the stitches (about 2 mm on one side) of the knitted bag body. A mold material was obtained in which the graphite tape and the carbon fiber were projected in a saw-tooth shape, and the saw-tooth-shaped projection portion bonded the graphite tape to the carbon fiber. This mold material was wound on a bobbin.

Next, the second mold material (graphite tape coated with carbon fiber) is wound around the core rod (inner mold) once, and the first mold material (graphite tape coated with metal wire). ) For 9 turns and the first mold material for 1 turn, the spiral wound body has an inner diameter of 50.1 mm,
It was set in a mold having an outer diameter of 69.9 mm and compressed by applying a load of 300 kgf / cm ² , to obtain a ring-shaped mold packing having a height of 10 mm and a density of 1.6 g / cm ³ .

The mold packing of the above-mentioned embodiment has an inner diameter of 5
A valve stuffing box having a diameter of 0.0 mm and an outer diameter of 70.0 mm was loaded with 6 rings, and then a lantern ring for leak detection was placed, and then the mold packing was loaded with 2 rings. After then tighten the packing at a surface pressure of 300kgf / cm ^2, 600 ℃ the valve, were introduced into the vapor of 250 kgf / cm ^2. In this case, to prevent the temperature of the gland part from dropping, the outer wall surface of the stuffing box is heated by 600 ℃.
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 is opened and closed at 00 mm / min, the sealing property is measured from the amount of steam leakage during this period, the packing height and the axial load are measured, and the compressibility is measured by the following formula (1) and the friction force is measured by the following formula (2). , Stop ventilation, cool the valve to room temperature, measure the packing tightening force, measure the stress relaxation rate by the following formula (3), take out each packing with a commercially available packing extraction tool, and measure the time required between them. Then, the heat loss of the packing was measured. Table 1 shows the results.

In the conventional product compared with the mold packing of the above-mentioned embodiment, the graphite tape is wound around the core rod (inner mold) once, and then the crimping body in which the wire mesh is crimped onto the graphite tape is wound 9 times. A spiral winding body made by winding one tape,
Set in a mold with an inner diameter of 50.1 mm and an outer diameter of 69.9 mm, and set it to 3
Height obtained by compressing with a load of 00 kgf / cm ² 10
The mold packing has a size of mm and a density of 1.7 g / cm ³ . Since the tape to which the wire net is pressed is hard, the conventional mold packing is hard and has a low compression rate, and the shaft conformability is poor. Therefore, the sealing performance is poor at low tightening pressure. Moreover, since the sticking of the packing tool becomes worse, the time taken out by the packing tool after use becomes longer.

[0024]

[Table 1]

[0025]

According to the present invention, the following effects can be obtained. (1) Since a flexible graphite sheet having a width of 6 mm or more has a large absolute value of tensile strength even in a single layer, it can be fed without breakage in the fiber coating process. (2) Even if the width of the flexible graphite sheet is 6 mm or less, the tensile strength can be increased by stacking multiple sheets, but when coated with a fiber material, due to the low friction characteristic of graphite, bending of the sheet When the action is performed, a longitudinal displacement between the sheets occurs, the displaced portion bulges into a bump, and forms a protrusion called a knot, but in the present invention, the flexible graphite sheet is a single layer, so the sheet In the longitudinal direction, no deviation occurs, and no fiber is formed to form nodules, so that a coated body having a uniform density can be obtained. (3) The flexible graphite sheet projects in a sawtooth shape from the stitches of the knitted bag body due to plastic deformation due to stretching, and since the sheet becomes micro-fragmented, the cover body having increased deformability of the sheet due to external force ( Mold material) is obtained. Therefore, the flexibility of the mold material is improved and the compressive deformability of the mold body is increased, so that the axial conformability of the compression molded mold packing is improved. As a result, the micro-gap between the shaft and the packing and the micro-gap inside the packing are reduced, so that the sealing performance of the mold packing is improved. (4) The knitted bag body covering the flexible graphite sheet is effective in preventing the graphite sheet from breaking during stretching, and also prevents collapse when the mold packing is loaded and hooks the tool when taking out the mold packing. The function as a member is exhibited. (5) The process of producing the molding material having the above-mentioned configuration and compressing the molding material into a molding body is suitable for mass production, and the cost of the molding packing can be reduced.

[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 mold material, (b) is a plan view of the stretched mold material, and (c) is a partially enlarged plan view. ,
(D) is a cross-sectional view taken along line XX, (e) is a cross-sectional view of a compression molding machine loaded with a mold material, and (f) is a perspective view of a compression-molded mold packing.

FIG. 2 is a perspective view of a mold material showing another embodiment of the present invention.

[Explanation of symbols]

 A Mold material 1 Flexible graphite tape 2 Braided bag 1a Folded portion 1b Projection due to plastic deformation of graphite tape 7 Mold packing

Claims (2)

(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 belt-shaped material is used as the mold material, which is dented and plastically deformed into a curl shape, and its widthwise both edges project in a sawtooth shape from the stitches of the knitting bag body, and this mold material is compressed in a spiral state. Molded packing characterized by being molded. 2. A step of knitting 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 projected in a sawtooth shape from the stitches of the knitting bag body to form a mold material. process and mold packing and its preparation, characterized by comprising more the step of compression molding the mold material spirally to put in <br/> molding frame ring to.