Pipe joints or couplings – Elbow
Reexamination Certificate
1998-12-28
2001-05-08
Nicholson, Eric K. (Department: 3629)
Pipe joints or couplings
Elbow
C285S903000, C285S423000
Reexamination Certificate
active
06227578
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an elbow which is suitable for connecting pipes, and a method for manufacturing such corrugated resin elbow. Although not elated directly to the size of the diameter of a pipe, this invention is mainly in the bent pipe portion of a large-sized pipe having an inside diameter of the order of 1,000 mm-2,000 mm.
2. Description of the Related Art
An conventional elbow of this type and a method for manufacturing the same is shown in
FIGS. 10
to
19
. A synthetic resin pipe P of a desired length includes a pipe wall
1
having a spirally corrugated shape. The synthetic resin pipe member P is cut in an inclined direction along a cutting line C having a desired inclination angle as shown in FIG.
11
. Then, as shown in
FIG. 12
, the thus cut and divided pipes are turned in the circumferential direction thereof to change the angles of the cut surfaces to thereby change the relative angle of the cut surfaces of the cut and divided pipes. Next, the cut end faces are butted against each other and are thereby connected with each other in a watertight manner (for example, see Japanese Patent Publication No. Hei. 4-44157, especially, FIG.
1
).
Referring here in more particular to the accompanying drawings, to manufacture an elbow E having an angle of 45° shown in
FIG. 14
, the middle portion of the spirally corrugated synthetic resin pipe member P is used as a pipe blank. As shown in
FIG. 10
, the synthetic resin pipe member P is cut along the cutting line C inclined at an angle of 22.5° with respect to a line intersecting at right angles to the longitudinal direction of the resin pipe member P to thereby divide the pipe member P into two pipe members p and p′. One pipe member p of the thus cut and divided two pipe members is rotated by 180° in the peripheral direction thereof to change the angle of the cut surface thereof to thereby change the relative angles of the cut surfaces of the cut and divided two pipe members p and p′ (See FIG.
11
and
12
). The cut end faces f and f of the two pipe members p and p′ are butted against each other (See FIG.
13
), then both sides of the butted surface F are connected together at a plurality of positions by wire members w such as wires. Next, sheet-shaped connecting material g, which is formed of the material that is similar to the pipe material and can be fused with the pipe material, is thermally fused and is thus applied repeatedly onto the outer periphery of the butted surface F to thereby close or seal spaces existing in the spirally corrugated cut surface of the butted surface F. The inner surface side portions of the pipe members p and p′ are similarly sealed to thereby connect together the two pipe members p and p′ in a watertight manner, thereby manufacturing the elbow E.
Now,
FIGS. 15
to
19
respectively show the time sequencing steps of a method for manufacturing an elbow having an angle of 90° shown in FIG.
19
. In the present elbow manufacturing method, as shown in
FIG. 15
, the two sides of the middle portion of a synthetic resin pipe member P to be used as a blank are cut along two cutting lines C and C respectively inclined at angles of 22.5° and −22.5° with respect to a line intersecting at right angles to the longitudinal direction of the pipe member P to thereby cut the pipe P into two side pipe members p, p and an intermediate pipe member p′. Then, the intermediate pipe member p′ is rotated by 180° in the circumferential direction thereof to thereby change the angles of the cut surfaces f′ and f′ thereof (See FIGS.
16
and
17
). Next, the cut surfaces f and f of the two side pipe members p and p are respectively butted against the cut surfaces f′ and f′ of the intermediate pipe member p′ (See FIG.
18
). Next, the thus butted surfaces F and F are connected in a watertight manner by similar means to the above-mentioned case, thereby manufacturing the elbow E. In addition, instead of the above-mentioned sheet-shaped connecting material, a glass fiber sheet is repeatedly applied using fused resin.
As described above, since, to manufacture this type of conventional elbow E, there is employed the means in which the spirally corrugated pipe is cut at a desired angle, the angles of the thus cut surfaces are changed and the present cut surfaces are butted against each other, and the butted surfaces are connected together again in a watertight manner. However, it takes labor, time and skill to seal positively the large spaces produced in the spirally corrugated portions of the butted surfaces to thereby connect the divided pipe members in a watertight manner. Furthermore, although the elbow E is manufactured by spending such time and labor, if the elbow E is vibrated or treated improperly during transportation, or if biased loads such as uneven loads are applied to the elbow E after it is buried in the earth, then water is easy to leak in the elbow E.
SUMMARY OF THE INVENTION
The present invention aims at solving the above-mentioned problems found in such conventional elbows and methods for manufacturing the same. Accordingly, it is an object of the invention to provide an elbow having a structure entirely free from water leakage as well as a technology capable of manufacturing such elbow easily and quickly.
The above-mentioned object can be attained by a corrugated resin elbow, according to a first aspect of the present invention, comprising:
a corrugate-shaped synthetic resin pipe wall including a plurality of valley portions, a plurality of ridge portions and side surfaces respectively interposed between the valley portions and the ridge portions,
in which at least one of a plurality of valley portions and the side surfaces which is disposed on the bend small diameter side of the substantially middle portion of the pipe wall in the longitudinal direction thereof is contractingly heated and deformed to thereby work the corrugate-shaped pipe wall into a bent attitude having a given angle.
In addition, the above-mentioned object can Be attained by a corrugated resin elbow, according to a second aspect of the present invention, comprising:
a corrugate-shaped synthetic resin pipe wall including a plurality of valley portions, a plurality of ridge portions and side surfaces respectively interposed between the valley portions and the ridge portions,
in which at least one of adjacent ridge portions and the side surfaces between the adjacent ridge portions which is disposed on the bend small diameter side of the substantially middle portion of a pipe wall in the longitudinal direction thereof is contractingly heated and deformed, in such a manner that the side surfaces are fused together or made to come close to each other, to thereby work the corrugate-shaped pipe wall into a bent attitude having a given angle.
Further, the above-mentioned object can be attained by a corrugated resin elbow, according to a third aspect of the present invention, comprising:
a corrugate-shaped synthetic resin pipe wall including a plurality of valley portions, a plurality of ridge portions and side surfaces respectively interposed between the valley portions and the ridge portions,
in which a plurality of valley portions which are disposed on the bend small diameter side of the substantially middle portion of a pipe wall in the longitudinal direction thereof are contractingly heated and deformed, in such a manner that the side surfaces disposed in adjacent to the substantially middle portion are fused together or made to come close to each other, to thereby work the corrugate-shaped pipe wall into a bent attitude having a given angle.
In these corrugated resin elbows according to any one of first to third aspect of the present invention, it is preferable that the pipe wall is a spirally corrugated form.
Further, in these corrugated resin elbows according to any one of first to third aspect of the present invention, it is preferable that the pipe wall is an annularly corrugated form.
Furth
Fukui Kouki
Kurimoto Isao
McGuireWoods LLP
Nicholson Eric K.
Totaku Industries, Inc.
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