JP2004257451A - Steel strip spirally coiled plastic tube end portion - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steel strip spirally coiled plastic tube end portion in which a steel strip spirally coiled portion is not loosened. <P>SOLUTION: In the steel strip spirally coiled plastic pipe end portion in which a spirally coiled steel strip is exposed, a plastic tube is exposed from a tip of the exposed steel strip, and a terminal piece comprising a metal piece body to be engaged with an inner surface of the plastic tube and a holding metal piece engaged with an outer surface of the plastic tube and located on the tip of the steel strip is fitted to the exposed plastic tube, an annular member for preventing the steel strip from being loosened is provided on an outer circumference of the tip side of the steel strip. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a terminal portion of a steel pipe spirally wound reinforced plastic pipe used as a fluid transport pipe, more specifically, a water pipe or a gas pipe.
[0002]
[Prior art]
Plastic pipes have better seismic resistance and workability than steel pipes that have been widely used in the past, and the amount used for water pipes and gas pipes has increased dramatically. For a transport pressure of 0.3 MPa or less, a single-layer plastic pipe is used. However, for a transport pressure higher than 0.3 MPa, the strength of the plastic pipe may be insufficient. It is conceivable to spirally reinforce the band.
[0003]
It is conceivable that a steel strip spirally wound plastic pipe end portion used for connecting such steel strip spirally wound plastic pipes to each other has a configuration as shown in FIG. FIG. 3 is a half-cut longitudinal sectional view of a conventional steel strip spiral wound plastic tube end portion. The steel strip helically wound plastic pipe has a structure in which a steel strip 11 spirally wound is provided on the outer circumference of a thermoplastic plastic pipe 10 of polyethylene or the like, and the outer circumference of the steel strip 11 is covered with a plastic protective layer 12. I have. The spirally wound steel pipe has a plastic protective layer 12 removed by a predetermined length to expose the spirally wound steel strip 11, and an end of the spirally wound steel strip is removed by a predetermined length to form an end of the plastic pipe 10. The part 10 'is exposed. In a portion where the spirally wound steel strip 11 is exposed, the copper wire 13 is tightly wound so that the spirally wound steel strip does not loosen.
[0004]
The terminal fitting 1 is attached to the end 10 ′ of the exposed plastic tube 10. The terminal fitting 1 includes a fitting main body 2 that engages with the inner surface of the end 10 ′, and a press fitting 3 that engages with the outer surface of the end 10 ′. The metal fitting main body 2 of the terminal fitting 1 includes an enlarged taper portion 2a for increasing the diameter of the end portion 10 'of the plastic tube 10 in a tapered shape, and an enlarged taper portion 2a on the enlarged diameter side of the enlarged taper portion 2a. And a flange portion 2b formed integrally. On the other hand, the presser fitting 3 includes an engagement portion 3a having an inner tapered shape to be engaged with the outer surface of the end portion 10 ', and a flange portion 3b formed integrally with the engagement portion.
[0005]
In the terminal fitting 1 having the above-described configuration, the enlarged taper portion 2b of the fitting main body 2 is inserted into the inner surface of the plastic tube exposed portion 10 ', and the engaging portion 3a of the holding member 3 is inserted into the outer surface of the plastic tube exposed portion 10'. In the engaged state, the flange 2b of the metal fitting body 2 and the flange 3b of the holding metal are fastened by the bolt 4, the nut 5, and the washer 6. In this state, the plastic tube is firmly sandwiched between the metal fitting main body 2 and the holding metal fitting 3, and can sufficiently withstand a tensile force. The flange of the presser fitting 3 is located at the tip of the spirally wound steel strip 11.
[0006]
[Problems to be solved by the invention]
However, in the end structure of the spirally wound plastic tube shown in FIG. 3, when the copper wire winding portion fixing the end of the spirally wound steel band without the plastic protective layer is damaged by corrosion or the like, the spirally wound steel tube is not used. There was a problem that the band was loosened and the plastic tube gradually expanded due to the internal pressure, resulting in breakage.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, a steel tube spirally wound plastic tube end portion according to claim 1 of the present invention exposes a spirally wound steel band and exposes a plastic tube from a tip of the exposed steel band. Then, a terminal fitting having a fitting main body engaging with the inner surface of the plastic pipe and a holding fitting engaging with the outer surface of the plastic pipe and located at the tip of the steel strip is attached to the exposed plastic pipe. A spirally wound steel pipe end portion provided with an annular member for preventing loosening of the steel strip at an outer periphery of a tip end side of the steel strip.
According to the above structure, even if the copper wire winding part is damaged, the steel member is prevented from loosening due to the presence of the annular member. In addition, since the steel strip does not advance loosely, swelling due to the internal pressure of the plastic pipe is minimized, and breakage of the plastic pipe can be prevented.
[0008]
In addition, the steel strip spiral wound plastic pipe end portion according to claim 2 of the present invention is characterized in that the annular member is provided integrally with the presser fitting. According to the above-described structure, it is possible to suppress the loosening of the steel strip, and to obtain a steel strip spirally wound plastic tube end portion which is easy to handle.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.
[0010]
[Example 1] Fig. 1 is a half-cut longitudinal sectional view showing a first embodiment of a steel strip spirally wound plastic pipe end portion according to the present invention. The steel strip helically wound plastic pipe has a structure in which a steel strip 11 spirally wound is provided on the outer circumference of a thermoplastic plastic pipe 10 of polyethylene or the like, and the outer circumference of the steel strip 11 is covered with a plastic protective layer 12. I have. The spirally wound steel pipe has a plastic protective layer 12 removed by a predetermined length to expose the spirally wound steel strip 11, and an end of the spirally wound steel strip is removed by a predetermined length to form an end of the plastic pipe 10. The part 10 'is exposed. In a portion where the spirally wound steel strip 11 is exposed, the copper wire 13 is tightly wound so that the spirally wound steel strip does not loosen.
[0011]
The terminal fitting 1 is attached to the end 10 ′ of the exposed plastic tube 10. The terminal fitting 1 includes a fitting main body 2 that engages with the inner surface of the end 10 ′, and a press fitting 3 that engages with the outer surface of the end 10 ′. The metal fitting main body 2 of the terminal fitting 1 includes an enlarged taper portion 2a for increasing the diameter of the end portion 10 'of the plastic tube 10 in a tapered shape, and an enlarged taper portion 2a on the enlarged diameter side of the enlarged taper portion 2a. And a flange portion 2b formed integrally. On the other hand, the presser fitting 3 includes an engagement portion 3a having a tapered inner surface which engages with the outer surface of the end portion 10 ', and a flange portion 3b formed integrally with the engagement portion.
[0012]
In the terminal fitting 1 having the above-described configuration, the enlarged taper portion 2b of the fitting main body 2 is inserted into the inner surface of the plastic tube exposed portion 10 ', and the engaging portion 3a of the holding member 3 is inserted into the outer surface of the plastic tube exposed portion 10'. In the engaged state, the flange 2b of the metal fitting body 2 and the flange 3b of the holding metal are fastened by the bolt 4, the nut 5, and the washer 6. In this state, the plastic tube is firmly sandwiched between the metal fitting main body 2 and the holding metal fitting 3, and can sufficiently withstand a tensile force. The flange of the presser fitting 3 is located at the tip of the spirally wound steel strip 11.
[0013]
The above configuration is the same as that of the conventional spirally wound steel pipe end portion of the steel pipe. A feature of the present invention is that a flange-shaped annular member 21 is formed integrally with the presser fitting 3. That is, the annular member 21 is formed integrally with the holding member 3 in a lower portion of the holding member 3 on the opposite side to the engaging portion 3a. Thereby, when a copper wire is damaged, loosening of a spirally wound steel strip can be suppressed. The inner diameter of the annular member 21 is more effective when the inner diameter is closer to the winding diameter of the steel strip. However, if the inner diameter of the annular member 21 is small enough to be in close contact with the steel strip surface, it is difficult to spirally wind the steel strip to the position of the presser fitting 3. Become. Also, it is necessary to have a margin for winding a copper wire around the spirally wound steel strip. As a result of the experiment, the inventor has found that if the inner diameter D1 of the annular member 21 satisfies D1 ≦ D2 × 1.2, assuming that the outer diameter of the spirally wound steel strip is D2, a sufficient effect can be obtained. . Further, it is desirable that the width of the annular member 21 is long, but it is effective if the width is 1/3 or more of the width of the steel strip, and it is desirable that the width is 1/2 or more of the width of the steel strip.
[0014]
FIG. 2 is a half-cut longitudinal sectional view showing a second embodiment of a steel strip spiral wound plastic tube end according to the present invention. The difference from FIG. 1 is that the annular member 21 is formed separately from the holding member 3, and the annular member 21 is made of a wire, a metal fitting, or the like to prevent the plastic tube from moving in the longitudinal direction. It is fixed to the presser fitting 3 by the tool 32. Other points are the same as those in FIG. 1, and the same parts as those in FIG.
According to the present embodiment, if the annular member is prepared, the conventional terminal fitting can be used as it is, so that the effects of the present invention can be obtained at low cost.
[0015]
【The invention's effect】
As described above, the steel strip spiral wound plastic pipe end portion of the present invention can prevent the plastic pipe from being broken because the annular member functions as a presser and prevents the spiral wound steel strip from loosening. Thus, a fluid transport pipe terminal portion can be obtained. Further, by providing the annular member integrally with the presser fitting, it is possible to suppress the loosening of the steel strip, and to obtain a steel strip helically wound plastic tube end portion which is easy to handle.
[Brief description of the drawings]
FIG. 1 is a half cut longitudinal sectional view showing a first embodiment of a steel strip spiral wound plastic pipe end portion of the present invention.
FIG. 2 is a half-section longitudinal sectional view showing a second embodiment of a steel strip spirally wound plastic pipe end portion of the present invention.
FIG. 3 is a half-cut longitudinal sectional view showing a conventional steel tube spirally wound plastic tube end portion.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Terminal metal fitting 2 Metal fitting main body 2a Diameter expansion taper part 2b Flange part 3 Holding metal part 3a Engaging part 3b Flange part 4 Bolt 5 Nut 6 Washer 10 Plastic pipe 10 'Plastic pipe exposed part 11 Spiral wound steel strip 13 Copper wire 21 Ring member 32 Slip stopper

Claims (2)

A spirally wound steel strip is exposed, and a plastic pipe is exposed from a tip of the exposed steel strip. A metal fitting body that is engaged with an inner surface of the plastic pipe is attached to the exposed plastic pipe. In a steel strip spirally wound plastic pipe end portion which is fitted with a terminal fitting having a holding fitting positioned at the tip of the steel strip, an annular member for preventing the steel strip from being loosened is provided on the outer periphery of the tip side of the steel strip. A spirally wound steel tube end portion of a steel strip provided. The said annular member is integrally provided with the said holding | maintenance metal fitting, The steel-band spiral wound plastic pipe terminal part of Claim 1 characterized by the above-mentioned.

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