Pipe joints or couplings – Serial,relatively movable portions – Having telescoping portion
Reexamination Certificate
1999-08-26
2001-06-26
Nicholson, Eric K. (Department: 3627)
Pipe joints or couplings
Serial,relatively movable portions
Having telescoping portion
C285S261000, C285S302000
Reexamination Certificate
active
06250690
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an expansion flexible tube joint and an assembling method thereof, and more particularly, to an expansion flexible tube joint which can be handled easily and is used for connecting water pipes, and because of its expanding flexibility, even when excessive external force is applied, the external force can be absorbed to prevent the tubes from being destroyed, and to an assembling method thereof.
2. Description of the Related Art
To already-existing tubes such as long water pipes provided on the ground or underground, various external forces such as compressing force, pulling force in the axial direction of the tube, or shearing force and bending moment in a direction perpendicular to the axial direction are applied due to ground subsidence or earthquake. If the external force is great, stress is concentrated on a tube joint which connects the already-existing tubes and the tube joint portion is destroyed. Therefore, it is necessary to absorb the external force applying to the water pipe portion to prevent the tube joint from being damaged.
Conventionally, a tube joint having a structure in which the tube joint itself can expand and contract is developed so as to absorb the external force to prevent the destruction. However, since this tube joint only move to expand and contract, the movable range is of two-dimensional, and this structure is not sufficient to cope with external force due to ground subsidence or earthquake.
To solve such a problem, there is developed a tube joint having a three-dimensional flexibility by employing a structure in which spherical surfaces are brought into contact with each other for sliding. In this case, as shown in
FIG. 10
, this expansion flexible tube joint A comprises a first cylindrical body
1
, a second cylindrical body
2
and a third cylindrical body
3
, and is connected to body tubes B at opposite flanges
6
through bolts
10
and nuts
11
. The first cylindrical body
1
comprises a pair of spherical surface ring members
1
,
1
made of cast iron and formed with partially spherical outer peripheral surface
4
. The second cylindrical body
2
comprises a sleeve
2
made of cast iron and inserted into the first cylindrical body
1
for relative movement from an axis direction of the cylindrical body. The third cylindrical body
3
comprises a pair of casing tubes
3
,
3
made of cast iron. The third cylindrical body
3
has an inner peripheral surface
5
for fitting over each of outer peripheral surfaces
4
of the first cylindrical body
1
, and is formed at its opposite ends with flanges which are connecting portions. Because the expansion flexible tube joint A is formed in this manner, the sleeve
2
, the spherical surface ring materials
1
,
1
and two casing tubes
3
,
3
are connected to one another such that they can extend and contract and move relative to one another. An end portion
3
a
of each of the casing tubes
3
is covered with a protective rubber cover
7
, thereby preventing earth, sand, dust and the like from entering into sliding portions.
Further, an annular peripheral groove
1
a
is formed in an inner peripheral surface of the spherical surface ring material
1
. An inner side of the annular peripheral groove
1
a
abuts against a C-shaped stainless steel lock-ring
17
having an angled cross section which is fitted and fixed to a recess formed in an outer peripheral surface of the sleeve
2
in the vicinity of its end. By this abutment, the relative movement range of the spherical surface ring material
1
and the sleeve
2
in the axial direction is limited. In
FIG. 10
, reference numbers
8
and
9
represent rubber seal rings.
In the case of this tube joint, when the outer peripheral surface
4
of the spherical surface ring material
1
swings while sliding on the inner peripheral surface of the casing tube
3
, the outer peripheral surface of the sleeve
2
contact the end portion
3
a
of the casing tube
3
so that the swinging range is determined, but this range is set to a constant small angle range. That is, the inner peripheral surface of the end portion
3
a
of the casing tube
3
is chamfered off, and its angle is constantly set to 15° and therefore, the swinging range of the tube joint is limited to the constant value.
However, in order to cope with megaseism or change with time of ground subsidence, development of small expansion flexible tube joint having excellent extending and retracting flexibility and capable of strongly exhibiting its function even if great external force is applied is highly required.
SUMMARY OF THE INVENTION
Thereupon, the present inventor researched and make every endeavor to develop the expansion flexible tube joint over the years and as a result, they improved the conventional expansion flexible tube joint, and completed an expansion flexible tube joint which has greater extending and retracting flexibility, the size can be reduced, and which is strong against external force.
An expansion flexible tube joint of the present invention comprises a first cylindrical body having a pair of spherical surface ring materials each formed with partially spherical outer surface, a second cylindrical body comprising a sleeve inserted into the first cylindrical body for relative movement thereof from an axial direction thereof, the sleeve provided at its end portion with stopper means for limiting extending and contracting movement relative to the first cylindrical body, and third cylindrical bodies fitted over both outer peripheral surfaces and comprising a pair of casing tubes each having slidable spherical inner peripheral surfaces and connection portions at opposite ends thereof, wherein an end inner peripheral surface of each of the third cylindrical bodies at the side thereof to which the second cylindrical body is inserted is chamfered, and the chamfered angle is 16° or greater, and the stopper means is mounted to an outer peripheral surface of the second cylindrical body and is formed into a closed ring shape.
With this structure, the bending angle of the second cylindrical body can be increased as compared with the conventional tube joint, the overall length of the tube joint can be shortened accordingly, the size can be reduced, the producing cost is reduced, the weight is also reduced so that the assembling operation is facilitated. Further, even if great external force is applied, since stopper means is strengthened such that the stopper means have high resistance force, the stopper means does not come out from the second cylindrical body easily. Therefore, even if great external force such as earthquake is suddenly applied, the expanding and contracting flexibility of the tube joint can be maintained strongly.
As a result, according to the present invention, it was possible to provide a small expansion flexible tube joint which is strong against the external force and have greater expanding and contracting flexibility.
It is preferable that the chamfered angle is 16 to 20°, and the chamfered angle is set smaller as an inner diameter of the second cylindrical body is greater.
Usually, a packing is inserted into between sliding surfaces of the first and third cylindrical bodies to enhance the watertightness, but according to the above structure, if the bending angle of the second cylindrical body is increased, it is possible to reduce the possibility that the packing inserted into between sliding surfaces of the first and third cylindrical bodies comes out with the rotational movement of the second cylindrical body. If the chamfered angle exceeds 20°, there is a possibility that the packing may come out as the second cylindrical body rotates, which is not preferable.
It is preferable that the stopper means is formed into a closed ring shape by connecting a connection jig to a C-ring by fixing means.
With this structure, even if a great external force such as megaseism is applied to the tube joint, the stopper means can not easily come out from the second cylindrical body so tha
Knobbe Marten Olson & Bear LLP
Nicholson Eric K.
Waterworks Technology Development Organization Co., Ltd.
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