JP3690615B2 - Electric fusion pipe fitting - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electric fusion pipe joint for joining thermoplastic pipes such as polyethylene pipes for gas pipes and water pipes by electric heating fusion. In particular, the present invention relates to an electric fusion pipe fitting suitable for a non-cutting method for digging a horizontal boring hole and laying a pipe by digging a horizontal boring hole without digging the ground at the time of pipe burying work. .
[0002]
[Prior art]
In recent years, polyethylene pipes have been frequently used as gas pipes having a small and medium diameter (25 to 300 mm). Polyethylene pipes are highly valued for their high corrosion resistance, lightness, and flexibility compared to steel pipes, which were the mainstay products before. Furthermore, paying attention to the flexibility of the polyethylene pipe, a non-cutting method is also employed in which piping is laid by drawing the polyethylene pipe around like a cable in a horizontal hole (boring hole) dug in the ground. Long-cut roads and piping are obstructive to road traffic and also require a large amount of work. Therefore, it is desirable to use non-open-cut methods as much as possible.
[0003]
The general supply form of the polyethylene pipe for gas is brought into the construction site as a coil pipe having a length of 90 to 30 m for a nominal diameter of 25 to 75A and as a straight pipe having a length of 5.5 or 9 m for a nominal diameter of 100A or more. It is. Therefore, when laying piping over longer distances (mostly), it is necessary to connect polyethylene tubes together. Here, a fusion method is generally used to connect the polyethylene pipes.
[0004]
FIG. 2 is a cross-sectional view showing a socket-type electrofused pipe joint used for butt connection of general polyethylene pipes and a state of connection work of polyethylene pipes using the same. The electrofused pipe joint 101 has a cylindrical shape as a whole, and its internal space is a connection hole 115 into which an end of the polyethylene pipe 103 is inserted. A coil-shaped heating wire 119 as an electric heating member is embedded in the inner surface of the connection hole 115 in the pipe joint body along the same surface. Between the inner diameter portion of the heating wire 119 and the inner surface of the connection hole 115, a resin layer (a part of the main body) having a thickness of the order of 0.1 mm exists. The heating wire 119 is connected to a terminal 123 provided on the outer surface of the pipe joint, and is fed with power from a connection terminal connected to the terminal.
[0005]
A stopper 125 is provided behind the connection hole 115 so as to protrude from the inner surface of the connection hole, and the end surface of the polyethylene pipe 103 inserted into the stopper 125 comes into contact with the stopper 125 to position the pipe. A region (cold zone 114) where the heating wire 119 is not embedded is present on the inner surface near the entrance of the connection hole 115. This part hardly melts at the time of electric fusion and does not melt. The resin melted in the hot zone flows into the cold zone and hardens, and does not come out of the pipe joint.
[0006]
However, the conventional electrofused pipe joint 101 in FIG. 2 protrudes considerably from the outer surface of the polyethylene pipe 103 to the outside, and becomes resistance when the pipe is drawn into the boring hole by the non-cutting method. For this reason, this conventional electric fusion pipe joint cannot be used for connecting pipes of the non-open cutting method. Specifically, the outer diameter of the electrofused pipe joint is 45 mm with respect to the outer diameter of 34 mm of a polyethylene pipe having a nominal diameter of 25A, and if the hole of the boring is enlarged to pass through this electrofused pipe joint. This is because the cross-sectional area of the boring hole is almost doubled and the construction cost is increased. It should be noted that the portion of the terminal 123 of the electrofused pipe joint 101 is to be deleted after the pipe is connected.
[0007]
As described above, since a socket-type electric fusion pipe joint cannot be used, the following butt fusion method is employed when connecting polyethylene pipes by a non-open cutting method. First, the end layers of both pipes are cut to remove a surface layer that may be altered. Next, the end surfaces of both pipes are aligned and the space between both end surfaces is opened again. During this opening, a heater heated to 210 ° C. is inserted, and the tube end surface is pressed against the heater to melt the same surface. After a certain period of time, the heater is removed and the molten end faces are butted together and pressurized. While pressure is applied, the system waits for cooling, and scrapes off any burrs that protrude from the outer surface of the joint after cooling.
[0008]
[Problems to be solved by the invention]
In this conventional butt fusion method, it is necessary to use a dedicated joining device. However, the joining device capable of joining a polyethylene pipe having a nominal diameter of 50 to 200 A has an overall weight of 300 kg and a price of 3 million yen. It is very heavy and expensive. Therefore, it takes time to set up the joining work, and the construction unit cost increases. Furthermore, joining work management is complicated.
[0009]
It is an object of the present invention to provide an electric fusion pipe joint that can perform a butt fusion work of thermoplastic pipes with a small and lightweight joining device, and that is easy and shortens the work time. Objective.
[0010]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the electric fusion pipe joint of the present invention is an electric fusion pipe joint in which two thermoplastic pipes are butt-joined by electric heat fusion; approximately equal to the inner and outer diameters of the pipe. A ring-shaped main body made of thermoplastics having inner and outer diameters, an electric heating member laid on an end surface of the ring-shaped main body, and a terminal for supplying electricity to the electric heating member.
[0011]
That is, in the conventional electric fusion pipe joint, the pipe joint surrounds the outside of the polyethylene pipe (thermoplastic pipe), whereas in the present invention, the pipe joint is between the end faces of the two polyethylene pipes to be joined. Is to be sandwiched. By doing in this way, since a pipe joint does not protrude outside a polyethylene pipe, it does not interfere with pipe drawing work into a boring hole.
[0012]
Here, the “electric heating member embedded in the pipe joint body” is a member that generates heat when energized, such as a heating wire, an electric heating film, a conductive resin layer, etc. It means a member that is buried or attached. Any material, structure, and installation method may be used as long as the electric fusion function of the electric fusion pipe joint is sufficiently realized.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, it will be described in more detail with reference to the drawings.
FIG. 1 is a cross-sectional view showing an electric fusion pipe joint according to an embodiment of the present invention and a state in which a polyethylene pipe is butt-joined using the joint.
The electric fusion pipe joint 1 has a ring-shaped main body 18. The outer diameter and inner diameter of the main body are substantially equal to the outer inner diameter of the polyethylene pipes 3 and 3 'to be connected. On both end faces 26 and 26 ′ of the main body 18, spiral heating wires 19 and 19 ′ as an electric heating member are laid (embedded). A resin layer (made of thermoplastic plastic) having a thickness of the order of 0.1 mm exists between the heating wires 19 and 19 ′ and the main body end surfaces 26 and 26 ′. The heating wire 19 is connected to a terminal 23 provided on the outer periphery of the main body. An external connection terminal (not shown) is connected to the terminal 23 to supply electricity from an external power source to the heating wire 19.
[0014]
End surfaces 27 and 27 'of the polyethylene pipes 3 and 3' are in contact with the end surfaces 26 and 26 'of the pipe joint main body. The alignment and pressing of the polyethylene pipes 3, 3 'and the pipe joint 1 are performed by a jig or tool not shown. At this time, the inner and outer peripheries of the pipe joint body 18 are substantially flush with the inner and outer peripheries of the polyethylene pipes 3 and 3 '. In this state, the heating wires 19 and 19 'are energized to fuse the polyethylene pipe end faces 27 and 27' and the pipe joint end faces 26 and 26 '.
[0015]
The operation of joining the polyethylene pipes in the embodiment of FIG. 1 is summarized as follows.
(1) The end surfaces of the polyethylene pipes 3 and 3 'are scraped to remove the altered layer on the surface.
(2) The end faces 27 and 27 'of the polyethylene pipes 3 and 3' are brought into contact with the end faces 26 and 26 'of the joint 1.
(3) The polyethylene pipes 3, 3 'and the pipe joint 1 are fixed using an appropriate clamp jig.
(4) Connect an external terminal to terminal 23.
(5) The heating wires 19 and 19 'are energized, and the end faces 27 and 27' of the polyethylene pipes 3 and 3 'and the end faces 26 and 26' of the pipe joint 1 are fused and integrated. At this time, the temperature of the fused portion may be controlled or managed using an appropriate temperature sensor or the like.
(6) Remove the external terminal and clamp jig. After this, the portions protruding outside the polyethylene pipes 3, 3 'such as the terminal 23 are scraped off. This completes the joining operation.
[0016]
At the time of fusing, it can be pushed by the hydraulic cylinder in a direction in which the polyethylene pipes 3 and 3 ′ are positively moved. Moreover, even if both polyethylene pipes are simply fixed with a jig, the pressure applied due to the temperature rise of the joint and the expansion accompanying melting is automatically applied to the joint surface. In some cases, it is not necessary to use a structure in which pressure is applied.
[0017]
【The invention's effect】
As is clear from the above description, the electrofused pipe joint of the present invention exhibits the following effects.
{Circle around (1)} Unlike conventional butt fusion (butt fusion) methods, an apparatus that strokes a polyethylene pipe in the axial direction is not required, so that the apparatus / tool to be used is simple and lightweight.
(2) Work management items are reduced, so that the work is simplified and the reliability of joining is improved.
(3) Since the shape is smaller than that of the conventional joint, the cost is reduced and the fusion time is also shortened.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an electrofused pipe joint according to an embodiment of the present invention and a state in which a polyethylene pipe is butt-joined using the joint.
FIG. 2 is a cross-sectional view showing a connection state of polyethylene pipes using a socket-type electric fusion pipe joint used for butt connection of general polyethylene pipes.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Electrofused pipe joint 3 Polyethylene pipe 11 Pipe inner hole 18 Ring-shaped main body 19 Heating wire 21 Main body inner surface 23 Terminal 26 Joint main body end surface 27 Pipe end surface

Claims (1)

An electric fusion pipe joint for butt joining two thermoplastic pipes by electric heat fusion;
A thermoplastic ring-shaped body having an inner and outer diameter substantially equal to the inner and outer diameters of the pipe;
An electric heating member laid on the end face of the ring-shaped body;
A terminal for supplying electricity to the electric heating member;
An electrofused pipe joint comprising:

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