Packing material and packing made of the same

This invention relates to a packing used in sealing two members. As the packing material, by using a material having the surface of a flexible graphite sheet cut to a width of less than 5 mm with fibers, or a material prepared by laminating a flexible graphite sheet cut to a width of less than 5 mm with at least one of reinforcing fiber of foil material, and covering its surface with fibers, or a material prepared by impregnating a principal component composed of flexible graphite particles with at least one of short fiber, rubber, resin or lubricant to form a bar-like structure and covering its surface with fibers, a packing material which can be either twisted or braided is obtained. By fabricating a packing by using any one of such packing materials, a cord-like packing is obtained without having to produce many packings matched to the dimensions of the members.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to packing material and packing preferably suitable 
to gland packing or the like for use in a shaft seal part of a hydraulic 
machine. 
2. Prior Art 
A variety of gland packings in which flexible graphite is used as a base 
material have been hitherto known for use in a shaft seal part or the like 
portion of a hydraulic machine, for example. 
Gland packings of this sort are manufactured by various techniques, such as 
laminating, die molding, chip molding, and ribbon packing. However, these 
techniques require that the graphite material must be previously molded 
into a ring shape conforming to the diametral size of a shaft with which 
such packing is to be used; as such, the packing cannot be used with any 
shaft having a different diameter. Therefore, such packing lacks 
versatility in use. Another, difficulty with such packing is that since 
flexible graphite is of low tensile strength and brittle in itself, once 
the packing is mounted in position it is extremely difficult to remove 
same when replacement is required, which means less usability. 
Further, the aforesaid manufacturing techniques individually have drawbacks 
of their own. The laminating technique involves the problem of poor yield, 
which leads to higher cost. Where the die molding or chip molding 
technique is employed, dies or metal molds are required, which means 
higher cost, and the packing produced is less versatile. The ribbon 
packing technique does not provide good workability. These difficulties 
may be overcome by forming the flexible graphite into a cord-like 
structure so that it may be used by being cut to a specified length 
conforming to the diameter of the shaft, as is the case with such other 
type of packing as fiber braided or knitted; but the trouble is that 
flexible graphite cannot be braided or knitted because, as pointed out 
above, it is in itself of low tensile strength and so brittle that its 
compressibility and allowable limit of twist are both extremely low. 
Therefore, it has hitherto been considered impossible to use such packing 
in such a way as is usual with the aforesaid fiber braided or knitted type 
of packing, that is, in such a way that the braided or knitted packing is 
cut to a length according to the diametral size of the shaft with which it 
is to be used, the so cut packing being then wound about the outer 
periphery of the shaft. 
SUMMARY OF THE INVENTION 
In order to overcome the aforesaid difficulties it is hence a primary 
object of this invention to present a packing material which can be either 
twisted or braided, and a twisted or braided cord-like packing by using 
the same packing material, by using a flexible graphite sheet cut to a 
width of less than 5 mm in order to advantageously utilize a 
characteristic feature of flexible graphite in sheet form in particular 
that if such sheet is cut to a width of less than 5 mm, both its 
compressibility and its allowable limit of twist are significantly 
increased as shown in FIG. 11 and FIG. 12, and by covering the flexible 
graphite sheet with a fiber material in order to attain the synergistic 
action of the fiber material and flexible graphite sheet. 
It is a second object of this invention to present a packing material which 
can be either twisted or braided and is small in elongation and high in 
strength, and a twisted or braided cord-like packing by using the same 
packing material, by using a flexible graphite sheet cut to a width of 
less than 5 mm, laminating this flexible graphite sheet with at least one 
of reinforcing fiber material or foil material, and covering this surface 
with the fiber material to attain the synergistic action of the fiber 
material and flexible graphite sheet, and the reinforcing fiber or foil 
material. 
It is a third object of this invention to present a packing material which 
can be either twisted or braided, and a twisted or braided cord-like 
packing by using the same packing material, by forming a bar mainly 
composed of flexible graphite particles and containing at least one of 
short fiber, rubber, resin or lubricant, and covering this surface with 
fiber in order to attain the synergistic action of the fiber material and 
the bar. 
It is thus intended to improve the usability and versatility. 
In the packing material of this invention, since a flexible graphite sheet 
cut to a width of less than 5 mm is used, the compressibility and the 
allowable limit of twist are increased to make it possible to twist or 
braid, and moreover since the surface is covered with fibers, the 
toughness against bending and sliding may be also enhanced. 
Furthermore, when a flexible graphite sheet cut to a width of less than 5 
mm is laminated with at least one of reinforcing fiber or foil material, 
the strength is further increased and the elongation is decreased. By 
covering this surface with the fiber, moreover, the toughness against 
bending or sliding may be improved. 
Meanwhile, by forming a bar by using flexible graphite particles as the 
base material and containing at least one of short fiber, rubber, resin or 
lubricant, twisting or braiding is enabled, and by adding at least one of 
short fiber, rubber and resin to the base material mainly composed of 
flexible graphite particles, the strength is increased and the elongation 
is restricted. When the surface is further covered with fiber, the 
toughness against bending or sliding may be improved. 
Therefore, any of the these packing materials permits a cord-like structure 
to be cut to a specified length conforming to the shaft diameter, which 
was impossible hitherto, and to be used as a gland packing by bending this 
cut cord-like structure in a ring form, so that the usability and 
versatility may be greatly enhanced.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the drawings, the present invention is described in 
details below. 
In FIG. 1, of the flexible graphite sheets less than 1 mm in thickness and 
less than 5 mm in width, six pieces of the most preferable flexible 
graphite sheet 1 measuring 0.38 mm in thickness and 3 mm in width are 
prepared, and the surface of these six flexible graphite sheets 1 is 
covered with knitted Aramid fiber or nickel-chromium-iron alloy fiber to 
form a knitting thread 4, and this knitting thread 4 is used as the 
packing material. 
FIG. 2 shows a cord-like packing, in which eight knitting threads 4 shown 
above are used, and are square braided to form a cord-like structure 5, 
and the surface of the knitting threads 4, that is, the surface of the 
knitted covering fibers is impregnated with at least one of silicone oil, 
scale-form graphite and rubber-based adhesive (or PTFE 
(polytetrafluoroethylene) instead of rubber-based adhesive), or with 
preferably these three sealers 6 together with zinc or sodium nitrite as a 
corrosion preventive. 
The packing in FIG. 3 is manufactured by bundling six knitting threads 4 
and roll forming while twisting 20 turns/m to form a cord-like structure 
5, and impregnating the surface of the knitting threads 4, that is, the 
surface of the knitted covering fibers with at least one of silicone oil, 
scale-form graphite and rubber-based adhesive (or PTFE instead of 
rubber-based adhesive), or preferably with these three sealers 6 together 
with zinc or sodium nitrite as a corrosion preventive. 
FIG. 11 presents experimental results on the relationship between cut width 
and compressibility with respect to a flexible graphite sheet having a 
thickness of 0.38 mm, and FIG. 12 presents experimental results on the 
relationship between cut width and allowable limit of twist with respect 
to a 1-meter long flexible graphite sheet having a thickness of 0.38 mm. 
It can be seen from these figures that the flexible graphite sheet has a 
characteristic feature that if its cut width is less than 5 mm, both its 
compressibility and its allowable limit of twist are remarkably increased. 
This fact assures easy and accurate formation of a packing in a cord-like 
structure 5 as shown in FIG. 2 and FIG. 3, from the packing material 
(knitting thread 4) having the surface of six flexible graphite sheets 1 
cut to a width of less than 3 mm with knitted Aramid fibers or nickel 
chromium-iron alloy fibers. In other words, eight-thread square braiding 
and also twisting can be satisfactorily carried out without breakage being 
caused to the flexible graphite sheet 1 or the core material, that is, to 
the knitting thread 4. Therefore, the cord-like structure 5 may be readily 
cut to a specified length conforming to the diameter of the shaft, for 
example, for use as a gland packing. This means improved usability and 
versatility. 
In FIG. 4, of the flexible graphite sheets less than 1 mm in thickness and 
less than 5 mm in width, three pieces of the most preferable flexible 
graphite sheet 1 measuring 0.38 mm in thickness and 3 mm in width are 
prepared, and these three flexible graphite sheets 1, and four lead foils 
7 of 0.1 mm in thickness and 3 mm in width are alternately laminated to 
form a core 3, and the surface of this core 3 is covered with knitted 
nickel-chromium-iron alloy fibers to form a knitting thread 4', which is 
used as the packing material. 
FIG. 5 shows a cord-like packing, in which eight knitting threads 4' shown 
above are used, and are square braided to form a cord-like structure 5', 
and the surface of knitting threads 4', that is, the surface of the 
knitted covering fibers is impregnated with at least one of silicone oil, 
scale-form graphite and rubber-based adhesive (or PTFE instead of 
rubber-based adhesive), or with preferably these three sealers 6 together 
with zinc or sodium nitrite as a corrosion preventive. 
The packing in FIG. 6 is manufactured by bundling six knitting threads 4' 
and roll forming while twisting 20 turns/m to form a cord-like structure 
5', and impregnating the surface of the knitting threads 4', that is, the 
surface of the knitted covering fibers with at least one of silicone oil, 
scale-form graphite and rubber-based adhesive (or PTFE instead of 
rubber-based adhesive), or preferably with these three sealers 6 together 
with zinc or sodium nitrite as a corrosion preventive. 
Also from such packing material (knitting thread 4') manufactured by 
alternately laminating three flexible graphite sheets 1 cut to a width of 
3 mm and four lead foils 7 to form a core 3, and covering the surface of 
this core 3 with knitted nickel-chromium-alloy fibers, a packing in 
cord-like structure 5' is obtained easilY and securely as shown in FIG. 5 
and FIG. 6. In other words, an eight-thread square braiding and also 
twisting can be satisfactorily carried out without breakage being caused 
to the flexible graphite sheet 1 or the core material, that is, to the 
knitting thread 4'. What is more, this knitting thread 4' is remarkably 
increased in strength owing to the intervening existence of lamination of 
lead foil 7, and since the surface is covered with knitting of 
nickel-chromium-iron alloy fibers, the bending performance is improved. 
Accordingly, the cord-like structure 5' can be cut to a specified length 
conforming to, for example, the diameter of the shaft for use as a gland 
packing, which means improved usability and versatility. 
FIG. 7 shows a modified example of the packing material in FIG. 4. Four 
flexible graphite sheets 1 of 0.38 mm in thickness are cut to a width of 3 
mm, and a reinforcing fiber 2 made of 0.15 mm.phi. nickel-chromium-iron 
alloy is laminated between the two layers in the top and bottom to form a 
core 3, and the surface of this core 3 is covered with knitted 0.1 mm.phi. 
INCONEL 600 fibers to form a knitting thread 4", which is used as the 
packing material. 
FIG. 8 shows a cord-like packing, in which eight knitting threads 4" shown 
above are square braided to form a cord-like structure 5", and the surface 
of the knitting threads 4", that is, the surface of knitted covering 
fibers is impregnated with at least one of silicone oil, scale-form 
graphite and rubberbased adhesive (or PTFE instead of rubber-based 
adhesive), or preferably with these three sealers 6 together with zinc or 
sodium nitrite as a corrosion preventive. 
FIG. 9 shows a cord-like packing, in which six knitting threads 4" are 
bundled, and are roll formed while twisting 20 turns/m to form a cord-like 
structure 5", and the surface of the knitting threads 4", that is, the 
surface of the knitted covering fibers is impregnated with at least one of 
silicone oil, scale-form graphite and rubber-based adhesive (or PTFE 
instead of rubber-based adhesive), or preferably with these three sealers 
6 together with zinc or sodium nitrite as a corrosion preventive. 
In FIG. 8 and FIG. 9, too, the cord-like structure 5" can be easily and 
securely formed by the knitting thread 4", and an eight-thread square 
braiding and twisting can be satisfactorily carried out without breakage 
being caused to the flexible graphite sheet 1 or the core material, that 
is, to the knitting thread 4". Still more, the strength is remarkably 
increased by the reinforcing fiber 2 and knitted covering fiber (INCONEL 
600), and the bending performance is also improved. Therefore, the 
cord-like structure 5" can be cut to a specified length conforming to the 
diameter of the shaft, for example, so as to be used as a gland packing, 
which means improved versatility and usability. 
FIG. 10 represents an example of the preparation of packing material, in 
which 60% flexible graphite particles, 25% natural graphite as lubricant, 
10% rubber, and 5% Aramid short fibers are kneaded, and a circular solid 
bar-like structure 8 of 3 mm.phi. is formed by an extrusion forming 
machine, and the surface of this bar-like structure 8 is covered with 0.1 
mm.phi. nickel-chromium-iron alloy fiber by knitting to form knitting 
thread 4"', which is used as the packing material. 
From such packing material, that is, knitting thread 4"', a cord-like 
packing can be formed by square braiding eight knitting threads 4"', to 
form a cord-like structure the same as in FIG. 5, and by impregnating the 
surface of the knitting threads 4"' with at least one of silicone oil, 
scale-form graphite and rubber-based adhesive (or PTFE instead of 
rubber-based adhesive), or preferably with these three sealers 6 together 
with zinc or sodium nitrite as a corrosion preventive. 
It is also possible to form a cord-like packing by bundling six knitting 
threads 4"', and roll forming while twisting by 20 turns/m to form a 
cord-like structure the same as in FIG. 6, and by impregnating the surface 
of the knitting threads 4"' with at least one of silicone oil, scale-form 
graphite and rubber-based adhesive (or PTFE instead of rubber-based 
adhesive), or preferably with these three sealers 6 together with zinc or 
sodium nitrite as a corrosion preventive. 
In order words, even from the packing material (knitting thread 4"') as 
stated above, a cord-like packing can be formed easily and securely, and 
eight-thread square braiding or twisting of the knitting threads 4"' can 
be satisfactorily carried out without breakage being caused to the 
bar-like structure 8 mainly composed of flexible graphite particles or the 
core material, that is, to the knitting threads 4"'. Still more, since 
rubber and Aramid short fibers are kneaded, the strength is significantly 
increased, and the bending performance is improved, and this cord-like 
packing can be cut to a specified length conforming to the diameter of the 
shaft for use, for example, as a gland packing, which means improved 
versatility and usability. 
As the reinforcing fiber 2 and covering fiber in the above embodiments, 0.1 
mm.phi. nickel-chromium-iron alloy is used, but it is not limitative, and 
other materials may be used depending on the purpose of such, for example, 
metal fibers such as MONEL and stainless steel, inorganic fibers such as 
asbestos, ceramic fiber, glass fiber and carbon fiber, and organic fibers 
such as cotton, rayon, phenol, Aramid, PBI (polybenzimidazole), PTFE 
(polytetrafluoroethylene), PEI (polyetherimide), PPS (polyphenylene 
sulfite), and PEEK (polyether etherketone). 
As the foil material, 0.1 mm thick lead foil is used in the example, but 
metal foils such as copper and aluminum, pulse sheet, Aramid sheet, PBI 
sheet, PTFE sheet, PEI sheet, PSS sheet, PEEK sheet and others may be used 
depending on intended use. 
As the short fiber to be kneaded with flexible graphite particles, in the 
above embodiment, Aramid short fiber was used, but it is not limitative, 
and other materials may be used depending on intended use, for example, 
metal short fibers such as nickel-chromium-iron alloy nickel-copper alloy 
and stainless steel, inorganic short fibers such as asbestos, ceramic 
fiber, glass and carbon, and organic short fibers such as cotton, rayon, 
phenol, Aramid, PBI, PTFE, PEI, PPS and PEEK. As the rubber, nitrile 
rubber, chloroprene rubber, fluororubber and others may be properly used 
selectively, and examples of resin may include, in particular, phenol 
resin and epoxy resin. As the lubricant, aside from the aforesaid natural 
graphite, expanded graphite, mica, petroleum wax and others may be used 
depending on intended use. 
In the illustrated example, the solid bar-like structure 8 is formed by 
extruding a mixed material mainly composed of flexible graphite particles, 
but the bar-like structure 8 may be formed in a circular solid section by 
rounding a flexible graphite sheet of less than 5 mm in width, or a 
flexible graphite sheet cut in a rectangular form with width of less than 
5 mm may be mixed together with at least one of short fiber, rubber and 
resin, and formed in a circular solid section. 
In the above embodiments, the knitting threads 4, 4', 4", 4"', are prepared 
by bundling a plurality of threads and twisting or braiding them, but it 
is also possible to compose a gland packing by twisting a single knitting 
thread 4, 4', 4" or 4"' so as to be suited to the dimensions or 
composition of the shaft seal part. 
Meanwhile, in the aforesaid embodiments, the knitting threads 4, 4', 4", 
4"' are square braided, but, of course, braiding by tubular plain stitch 
or lattice braiding may be used. 
As the covering fiber, aside from the knitting shown above, tubular plain 
stitch, conduit knitting or tubular weaving may be applied, too. 
The measured data of knitting threads are shown in Table 1. 
TABLE 1 
__________________________________________________________________________ 
Use in manufacture 
Core Surface covering 
Properties Processability 
No. 
Material Process 
Material Process 
Strength kg 
Elongation % 
Twist Braid 
__________________________________________________________________________ 
1 Corresponding to 
Laminate 
Aramid Knitting 
4.5 15.8 Possible 
Possible 
FIG. 1 of this invention 
(spun yarn) count 20 
2 Corresponding to 
" nickel-chromium- 
" 5.7 10.0 Possible 
Possible 
FIG. 1 of this invention 
iron alloy 600 
0.1 mm.phi. 
3 Corresponding to 
" nickel-chromium- 
" 7.2 5.3 Possible 
Possible 
FIG. 7 of this invention 
iron alloy 600 
0.1 mm.phi. 
4 Corresponding to 
" nickel-chromium- 
" 5.0 9.2 Possible 
Possible 
FIG. 4 of this invention 
iron alloy 600 
0.1 mm.phi. 
5 Extrusion forming of flexible 
Extrusion 
nickel-chromium- 
" 0.8 1.5 Impossible 
Impossible 
graphite powder 3 mm.phi. 
iron alloy 600 
0.1 mm.phi. 
6 Corresponding to 
Kneading, 
nickel-chromium 
" 3.8 4.1 Possible 
Possible 
FIG. 10 of this invention 
extrusion 
iron alloy 600 
0.1 mm.phi. 
__________________________________________________________________________ 
As clear from Table 1, the packing materials No. 1, No. 2, No. 3, No. 4 and 
No. 6 of this invention, are higher in strength and smaller in elongation 
as compared with the packing material No. 5, and it is also known that 
twisting and braiding can be carried out satisfactorily. 
In the above embodiments, it is explained that the knitting threads 4, 4', 
4", 4"' are braided to be used as gland packing, but not limited to such 
gland packing, by ribbon stitching or plain stitching of knitting threads 
4, 4', 4", 4"', it may be possibly applied as a sealing packing between 
static members, and in this case, too, the same action and effect as in 
fabrication of glad packing will be obtained. 
Thus, in the packing material and packing according to this invention, 
being composed of flexible graphite, it is not necessary to make as many 
packings as the number of different dimensions of shaft seal members, and 
bending and toughness are improved, and it may be preferably used as the 
gland packing or sealing material of static members.