JP2585292B2 - How to connect pipes - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for connecting a pipe made of a polyolefin-based synthetic resin for transporting a fluid.

BACKGROUND ART A typical prior art is shown in FIG. End faces 1a, 2a of tubes 1, 2 made of synthetic resin such as polyolefin are heated using a tool having a parallel heating surface prepared in advance,
The ends 1a and 2a are softened, and the tubes 1 and 2 are pressed in the axial direction toward each other in the molten state, and the butt connection is performed.

In the butt condition shown in FIG.
A heating tool for heating the end faces 1a, 2a of 2 is required,
Work on site becomes complicated. In addition, the end face 1
In the work of heating the tubes a and 2a and then pressing the tubes 1 and 2 in the axial direction toward each other, it is necessary to set the heating temperature, time, pressure, etc. accurately. There is a problem of needing.

Another prior art is a bayonet fitting shown in FIG. The ends 3a and 4a of the synthetic resin tubes 3 and 4 are fitted and inserted into the ends 5a and 5b of the socket 5 made of a synthetic resin to perform connection. In order to heat the outer peripheral surface of the end 3a of the tube 3 and the inner peripheral surface of the end 5a of the socket 5, a heating tool 6 shown in FIG. 6 is used. By the heating surfaces 7 and 8 of the heating tool 6, the outer peripheral surface of the end 3a of the tube 3 and the inner peripheral surface of the end 5a of the socket 5 are heated and softened and melted, respectively. A similar connection operation is performed on the end 4a of the other tube 4 and the end 5b of the socket 5.

In such a plug-in connection fitting shown in FIG. 5, the tool 6 shown in FIG. 6 is required, and the work on site becomes complicated. Also, the heating temperature during the connection work,
It is necessary to set time and pressure accurately, and there is a problem that a skilled person is required.

Yet another prior art is shown in FIG. The ends of the synthetic resin tubes 9 and 10 are fitted into a socket 11 made of synthetic resin. In the socket 11, a heating wire 12, such as a nichrome wire, is embedded in a coil shape. With the tubes 9, 10 partially fitted in the socket 11, the heating wire 12 is connected to a power source to generate Joule heat, so that the tubes 9, 10 and the socket 11 are softened and melted. The connection is made.

In the prior art shown in FIG. 7, the heating wire 12 remains when the connection is completed. This heating wire 12 is
The synthetic resin that is the material of the socket 10 and the socket 11 is oxidized and deteriorated, thereby deteriorating the sealing performance,
The strength may be reduced. Further, since the heating wire 12 is coil-shaped, and the coil wires have intervals in the tube axis direction, the portion to be melted cannot be heated with a uniform temperature distribution. However, the performance of improving the mechanical strength cannot be expected, and it is difficult to ensure the sealing performance and the mechanical strength.

Problems to be Solved by the Invention An object of the present invention is to provide a pipe connecting method which has improved workability, does not require skill, has improved productivity, and has improved reliability such as sealing performance and mechanical strength. It is to be.

Means for Solving the Problems The present invention provides a pair of pipes to be connected made of a polyolefin-based synthetic resin, and a joint body made of a polyolefin-based synthetic resin. A carbon fiber layer is embedded over the entire length and over the entire circumferential direction, and the ends of the pipes are fitted into the ends of the joint body, and are exposed at both ends in the axial direction of the joint body. A pair of terminal members are brought into contact with the carbon fiber layer substantially all around in the circumferential direction, a power source is connected between the terminal members, and power is supplied to the carbon fiber layer at a uniform current density through the terminal members. Accordingly, the synthetic resin on the outer peripheral surface at the end of the pipe and the inner peripheral surface at the end of the joint body is melted, and solidified and integrated after melting of the synthetic resin. Is the way.

Further, the present invention is characterized in that the joint main body is given in advance a residual strain that contracts in a radial direction by heating.

According to the present invention, carbon fibers are embedded in the joint body in a state where the polyolefin-based synthetic resin pipe and the joint body are fitted to each other, and the carbon fibers are heated by electric power. Therefore, the polyolefin-based synthetic resin tube and the joint body are melted, whereby the paired polyolefin-based synthetic resin tube and the joint body are air-tightly connected to each other. Therefore, the workability is improved, and without the need for tools for heating as described in connection with the prior art described above, and without the need for skill in the work, the airtightness is improved with high quality, and A connection with improved strength is possible.

Embodiment FIG. 1 is a sectional view of an embodiment of the present invention.
Are connected by a joint body 17 to form a synthetic resin pipe joint. The pipes 15, 16 and the joint body 17 are made of a polyolefin-based thermoplastic synthetic resin material such as polyethylene, polypropylene, and polybutene. Ends 15a, 1 of tubes 15,16
6a is fitted to ends 17a and 17b of the joint body 17, respectively.

FIG. 2 is a sectional view taken along the axis of the joint body 17, and FIG.
The figure is a sectional view perpendicular to the axis of the joint body. Inside the joint body 17, a carbon fiber layer 18 is formed. This carbon fiber layer 18
It is embedded in the joint body 17 and has a configuration in which only cotton-like carbon fibers or a processed carbon fiber product is dispersed in a synthetic resin. The processed carbon fiber product is a processed carbon fiber product such as cotton, cloth, net, chop, and filler. The joint main body 17 is given in advance a residual strain that contracts inward in the radial direction by heating.

With the ends 15a, 16a of the tubes 15, 16 fitted to the ends 17a, 17b of the joint body 17, as shown in FIG.
8 is connected to a DC or AC power supply 21 via annular terminal members 19 and 20. As a result, the carbon fiber layer 18 is heated to generate Joule heat, and the joint body 17 and the pipes 15, 1
The end portions 15a and 16a of 6 and the vicinity thereof are heated and softened and melted. As a result, the ends 15a, 16a of the pipes 15, 16 and the joint body 17
And the ends 17a and 17b are airtightly connected. In this way, between the inner peripheral surfaces of the ends 17a and 17b of the joint body 17 and the ends 15a and 16a of the pipes 15 and 16 fitted to the inner peripheral surfaces, respectively, extend over the entire length in the axial direction. Then, over the entire circumferential direction, the polyolefin-based synthetic resin enters the carbon fiber and is melted and solidified to form a pipe joint.

When the joint body 17 is heated, its inner peripheral surface contracts so as to press the outer peripheral surfaces of the ends 15a, 16a of the tubes 15, 16 inward in a radial direction. Strong connection between the ends 15a, 16a and the ends 17a, 17b of the joint body 17 becomes possible,
The airtightness and the mechanical strength are improved. The state in which the connection has been completed is shown in FIG. 1 (2). The terminal members 19 and 20 are made of metal or an object coated with a copper or silver paste or the like, and have a low contact resistance with the carbon fiber layer 18; Or it may be C-shaped, surrounding the tubes 15, 16 and also
It is configured so that it can be removed from 16.

According to such an embodiment, the same synthetic resin material is mutually fused between the outer peripheral surfaces of the ends 15a, 16a of the pipes 15, 16 and the inner peripheral surfaces of the ends 17a, 17b of the joint body 17. Therefore, the airtightness can be improved and the mechanical strength can be improved.

Since the carbon fiber layer 18 is formed over the entire length of the joint body 17 in the axial direction and over the entire circumference thereof, it is possible to perform heating with a uniform temperature distribution over the entire surface of the joint body 17. Accordingly, the quality of the connection can be improved by making the softened and molten state of the joint body 17 and the pipes 15 and 16 uniform. However, the contraction force due to the residual strain of the joint body 17 is grounded, and can be uniformly generated on the inner peripheral surface of the body 17. This can also improve the quality of the connection.
Furthermore, after the connection is completed, the carbon fiber layer 18 remains in the joint main body 17, and this carbon fiber layer 18 improves the strength of the joint main body 17 and the ends 15a, 16a of the pipes 15, 16. Become. In particular, since the carbon fiber layer 18 is arranged at an interval radially outward from the inner peripheral surface of the joint main body 17, it is possible to improve the bending strength after the connection is completed.

The carbon fibers forming the carbon fiber layer 18 do not cause deterioration of the polyolefin-based synthetic resin material constituting the joint body 17 even when used for a long period of time, and can maintain a stable connection state for a long period of time Becomes Therefore, in comparison with the configuration in which a heating wire such as a nichrome wire described in connection with the above-described prior art is embedded in place of the carbon fiber layer 18, the configuration is superior in that it does not change over time, and the cost is low. There is an advantage that it is reduced.

In place of socket 17, an elbow may be used, a chi may be used, a regiucer, a saddle, etc.,
The present invention can be widely applied to other pipes and joint bodies made of polyolefin-based synthetic resin.

Effects As described above, according to the present invention, workability is improved, and a tool or the like having a specially devised configuration is not required.
A connection with improved airtightness and mechanical strength can be performed without requiring a skilled worker. In addition, it is possible to heat portions of the pair of synthetic resin tubes that are in a mutually fitted state with a uniform temperature distribution, thereby improving airtightness and mechanical strength. .

Furthermore, since the conductive fibers are embedded in the fitting portion, the synthetic resin tubes and the like that form a pair to be connected are connected by softening or melting the synthetic resin materials. This also makes it possible to improve the sealing performance and the mechanical strength.

Furthermore, it is important that the aging can be suppressed, the sealing performance can be maintained for a long period of time, and particularly the large strength of the carbon fiber can be maintained.

In particular, according to the present invention, the pair of pipes to be connected and the joint body into which their ends are inserted are both made of polyolefin-based synthetic resin, and each inner peripheral surface at the end of the joint body. The synthetic resin entered the carbon fiber existing between the inner peripheral surface and the outer peripheral surface of the end of each tube fitted to the respective inner peripheral surface to form a carbon fiber layer integrated by melting and solidifying. However, in the pipe joint having such a configuration, since the connection operation is performed by supplying electric power to the carbon fiber layer, the connection operation is easy as described above, and an expert is not required for the operation.

Further, the carbon fiber does not oxidize like the heating wire 12 which is the metal coil described in connection with FIG. 7 described above, and thus does not oxidize the polyolefin-based synthetic resin and deteriorates the quality. Thus, the carbon fiber does not deteriorate the sealing performance and does not lower the strength. Rather, the carbon fiber achieves an excellent effect of increasing the strength.

Further, according to the present invention, by supplying electric power to the carbon fiber layer, an excellent effect that a portion to be melted can be heated with a uniform temperature distribution is achieved. This is an excellent effect that cannot be attained by the prior art using the heating wire 12 which is a metal coil described in connection with the drawing, and in the present invention, the sealing performance and the mechanical strength are compared with this prior art. , And the reliability can be improved.

Further, according to the present invention, since the synthetic resin enters the carbon fiber and is melted and solidified to be integrated, the heating wire, which is a metal coil in the prior art described with reference to FIG. In the present invention, there is no danger that the sealing performance and the mechanical strength are reduced due to separation.

Further, in the present invention, no adhesive is interposed between the inner peripheral surface at the end of the joint body and the outer peripheral surface at the end of each pipe, and the joint body and the pipe are melted and solidified to form an integral body. As described above, the sealing performance and the mechanical strength can be improved as described above, and since such an adhesive is not required, the pipe and the joint body are different types of synthetic resin. Without being connected through a layer of adhesive,
Both the pipe and the joint body are made of a polyolefin-based synthetic resin, so that the sealing performance and the mechanical strength are improved as described above. Further, since such an adhesive is not used in the present invention, there is also an effect that workability is good.

In the present invention, the pair of terminal members are respectively in contact with the carbon fiber layers exposed at both ends in the axial direction of the joint main body, and the terminal members are in contact with the end portions of the carbon fiber layers substantially all around the circumferential direction. Therefore, electric power can be supplied to the carbon fiber layer at a uniform current density, so that the outer peripheral surface of the end of the pipe and the inner peripheral surface of the end of the joint body are heated and melted at a uniform temperature distribution. As a result, airtightness is reliably achieved, and the strength becomes uniform over the entire circumference in the circumferential direction, thereby improving reliability.

According to the present invention, the carbon fiber layers are embedded inside the joint body, and are therefore arranged radially outward from the inner peripheral surface of the joint body 17, Accordingly, an excellent effect that the bending strength after completion of the connection between the pipe and the joint main body can be achieved is also achieved.

[Brief description of the drawings]

FIG. 1 is a sectional view of one embodiment of the present invention, and FIG. 2 is a joint body.
FIG. 3 is a sectional view of the joint body 17 at right angles to the axis, and FIG.
Fig. 5 is a cross-sectional view showing the structure of a butt connection pipe joint of the prior art, Fig. 5 is a cross-sectional view showing the structure of a bayonet connection pipe joint of the prior art, and Fig. 6 is a tool 6 used in the prior art of Fig. 5. 7 is a cross-sectional view of another prior art. 15, 16… synthetic resin tube, 17… fitting body, 18… carbon fiber layer

Claims (2)

(57) [Claims] 1. A pair of pipes made of a polyolefin-based synthetic resin to be connected and a joint body made of a polyolefin-based synthetic resin are prepared. Inside the joint body, the entire length in the axial direction and the circumferential direction are provided. A carbon fiber layer is embedded over the entire surface, and the ends of the pipes are fitted into the ends of the joint body, and are substantially exposed to the carbon fiber layers exposed at both ends in the axial direction of the joint body. A pair of terminal members are brought into contact with the entire circumference, respectively, a power source is connected between the terminal members, and power is supplied to the carbon fiber layer at a uniform current density through the terminal members. A method for connecting pipes, wherein the synthetic resin on an outer peripheral surface of an end and an inner peripheral surface of an end of a joint body is melted, and solidified and integrated after melting of the synthetic resin. 2. The pipe connecting method according to claim 1, wherein the joint body is preliminarily provided with a residual strain that shrinks in a radial direction by heating.