Pipe joints or couplings – Particular interface – Annular socket
Reexamination Certificate
2001-07-11
2003-02-11
Nicholson, Eric K. (Department: 3679)
Pipe joints or couplings
Particular interface
Annular socket
C285S423000, C285S354000
Reexamination Certificate
active
06517123
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a pipe joint made of resin which is preferably used in piping for a liquid having high purity or ultrapure water to be handled in a production process in, for example, the production of semiconductor devices, the production of medical equipment and medicines, for food processing, and in the chemical industry.
2. Description of the Prior Art
Conventionally, as pipe joints made of resin of this kind, those having a configuration like that shown in
FIGS. 4
to
6
are known. Among them, the pipe joint made of resin shown in
FIG. 4
(see Japanese Utility Model Publication No. 7-20471) comprises a joint body
1
, a sleeve
2
, and a union nut
3
which are made of resin. In the joint body
1
, a pipe receiving port
5
is formed at one end in the axial direction. A first sealing portion
6
is formed in an inner area of the pipe receiving port
5
, and a second sealing portion
7
is formed in an entrance area of the pipe receiving port
5
so that the sealing portions intersect the axis C of the joint body
1
. An external thread portion
9
is formed on the outer periphery of the pipe receiving port
5
. In the sleeve
2
, a fitting portion
10
having an outer diameter that allows the portion to be fitted into the receiving port
5
of the joint body
1
is formed in an inner end portion in the axial direction, and a bulge portion
15
having a mountain-like section shape is formed in an outer end side in the axial direction. The sleeve
2
is pressingly inserted into one end portion
17
of a tube
11
made of resin under a state where the fitting portion
10
is projects outwardly. As a result of this press insertion, the diameter of the one end portion
17
of the tube
11
is increased. An inner end sealing portion
13
which abuts against the sealing portion
6
of the joint body
1
is formed in an end portion of the fitting portion
10
, and an outer peripheral sealing face
18
which abuts against the sealing portion
7
of the pipe receiving port
5
is formed in a place corresponding to the bulge portion
15
. In the union nut
3
, an internal thread portion
20
which is to be screwed to the external thread portion
9
of the joint body
1
is formed.
The one end portion
17
of the tube
11
into which the sleeve
2
is pressingly inserted is inserted into the receiving port
5
of the joint body
1
. Under this state, the internal thread portion
20
of the union nut
3
which is previously loosely fitted onto the outer periphery of the one end portion
17
of the tube
11
is screw-fastened to the external thread portion
9
of the joint body
1
. This fastening causes the sleeve
2
to be pressed in the axial direction, so that the inner end sealing portion
13
and the outer peripheral sealing face
18
of the sleeve
2
abut against the sealing portions
6
and
7
of the pipe receiving port
5
of the joint body
1
, respectively, thereby exerting a sealing function.
In the pipe joint made of resin shown in
FIG. 5
, a tapered sealing portion
30
in which the diameter is gradually reduced toward the inner side in the axial direction is formed in an entrance area of a receiving port
5
of a joint body
1
into which the one end portion
17
of the tube
11
made of resin is to be inserted, and a sealing portion
31
which abuts against a tapered sealing portion
30
is formed in the inner end of a sleeve
2
. The sleeve
2
is fitted onto the one end portion
17
of the tube
11
, whereby a bulge portion
32
which is locally projected toward the radially inner side is formed on the one end portion
17
of the tube
11
. The internal thread portion
20
of the union nut
3
which is previously loosely fitted onto the outer periphery of the one end portion
17
of the tube
11
is fastened to an external thread portion
9
of the joint body
1
. This fastening causes the sleeve
2
to be pressed in the axial direction, so that sealing portions
30
and
31
abut against each other, thereby exerting a sealing function.
In the pipe joint made of resin shown in
FIG. 6
, a tapered sealing portion
33
in which the diameter is gradually reduced toward the inner side in the axial direction is formed in an entrance area of a receiving port
5
of a joint body
1
into which the one end portion
17
of the tube
11
made of resin is to be inserted. A sleeve
2
which has an outer peripheral wall
34
having a trapezoidal section shape is pressingly inserted into the inner periphery of the one end portion
17
of the tube
11
. As a result of this press insertion, a bulge portion
35
which is locally projected toward the radially outer side along the outer peripheral wall
34
of the sleeve
2
is formed on the tube
11
. The internal thread portion
20
of the union nut
3
which is previously loosely fitted onto the outer periphery of the one end portion
17
of the tube
11
is fastened to an external thread portion
9
of the joint body
1
, A whereby the bulge portion
35
of the tube
11
and the sleeve
2
are pressed against the joint body
1
and an inclined face
36
on the tube end side of the bulge portion
35
is pressed against the tapered sealing portion
33
in the axial direction, so as to exert a sealing force.
As described above, all of the conventional pipe joints made of resin shown in
FIGS. 4
to
6
comprise: the joint body
1
which is made of resin, and which has the pipe receiving port
5
in one end portion, and the external thread portion
9
on the outer periphery of the pipe receiving port
5
; the sleeve
2
which is made of resin, and which is to be pressingly inserted into the inner or outer periphery of the one end portion
17
of the tube
11
made of resin to be integrated therewith; and the union nut
3
which is made of resin, which is loosely fitted onto the outer periphery of the one end portion
17
of the tube
11
, and which is screwed via the internal thread portion
20
to the external thread portion
9
of the joint body
1
. The one end portion
17
of the tube
11
into which the sleeve
2
is pressingly inserted to be integrated therewith is inserted into the pipe receiving port
5
of the joint body
1
. The gap between the one end portion
17
of the tube
11
and the pipe receiving port
5
of the joint body
1
is sealed in a water blocking manner via the sleeve
2
which is pressed against the joint body
1
by fastening the union nut
3
.
In all of the conventional pipe joints made of resin, the external thread portion
9
of the joint body
1
and the internal thread portion
20
of the union nut
3
use triangular threads according to usual thread standards. Such triangular threads have an included angle of 55° or 60° (see FIG.
4
).
However, usual thread standards are originally introduced for metals, and, in some cases, are not suitable to threads for resin such as those for a pipe joint made of resin because, when a pipe joint is made of resin, creep deformation which advances over time under a constant load is largely affected by the load and the temperature.
In the pipe joint made of resin in which the sleeve
2
and the joint body
1
are pressed against each other by fastening the union nut
3
, a creep phenomenon and stress relaxation due to the phenomenon occur in a portion where the sleeve
2
and the joint body
1
are pressed, thereby causing the liquid to leak or the tube
11
to slip off. Therefore, functions which are exerted by pressing the two components, i.e., the sleeve
2
and the joint body
1
, such as the sealing function, and the function of preventing the tube
11
from slipping off must be ensured. Therefore, it is required to set a pressing force which is necessary and sufficient for exerting functions such as the sealing function. In the case where a creep phenomenon or the like occurs and the union nut
3
is to be further fastened, adjustment of the pressing force must be performed at a higher degree.
As the resin material of a pipe joint of this kind, fluororesin which has excellent heat resi
Jones Tullar & Cooper P.C.
Nicholson Eric K.
Nippon Pillar Packing Co. Ltd.
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