JPH0780940A - Fusion bonding of pipe materials - Google Patents

Abstract

PURPOSE:To provide a fusion bonding method eliminating the protrusion of a bead toward the inner surface of a pipe and preventing the formation of a fine gap on the inner surface of a bonded part. CONSTITUTION:Inclined surfaces are provided to the pipe end surfaces of pipe materials P1, P2 to be connected and, in such a state that the pipe end parts of the pipe materials are abutted, the outer periphery of the bonded part of both pipe materials is covered with an electrofusion joint J and a current is supplied to the joint J. By this constitution, the inner surface of the joint and the outer surfaces of the pipe materials are heated and melted to fuse and bond the pipe materials and the joint and the thermally expanded molten resin (generated by melting the inner surface of the joint) M closely fills the gap between the abutted pipe end surfaces F11, F2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for fusion-bonding a pipe material formed of a thermoplastic resin.

[0002]

2. Description of the Related Art As a method for connecting pipe materials of a thermoplastic resin molded product, there is a method in which each pipe end portion of the pipe material is melted by heating with a heater and then the respective melted portions are butted.

However, in the butt fusion welding method,
Conventionally, the pressure at the time of butting has extruded the molten portion of the pipe material toward the inner surface and the outer surface side and raised it, and a bead has been generated at the joint portion. Thus, if a bead is formed on the inner surface side of the pipe, it causes adverse effects such as pressure loss and stagnation of the fluid. Therefore, the inner surface bead is required to be minimized. Especially when the construction pipe is for clean use,
The demand is great.

Therefore, conventionally, as shown in FIG. 2, for example, after the pipe end faces of the pipe members P21 and P22 to be connected are heated and melted by a heater (a), when they are butted and joined, As shown, a measure is taken such that a core-shaped insertion member C is arranged on the inner surface of the joint to prevent the bead from protruding toward the inner surface of the pipe (for example, Japanese Patent Laid-Open No. 3-2585).
No. 26).

[0005]

By the way, according to the above-mentioned countermeasure (beadless treatment), the bead that attempts to protrude toward the inner surface of the pipe is forcibly crushed, so that the bead height is almost the same level as the inner surface of the pipe. On the other hand, as shown in FIG. 2 (c), a minute gap is created between the bead B and the inner surface of the tube, which causes a new problem that microorganisms may propagate there. Further, after the fusion bonding is completed, it is necessary to pull out the core-shaped insertion member C, but this pulling out may be difficult.

The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a fusion bonding method in which a bead does not protrude to the inner surface of a pipe and a fine gap is not formed on the inner surface of the joint. And

[0007]

In order to achieve the above object, the joining method of the present invention is, as shown in FIG. 1 corresponding to the embodiment, a pipe end surface of each of two pipe members P1 and P2 for connection. F1,
F2 is processed into a shape that is inclined at a specified angle with respect to the center of the pipe, and the ends of these pipes are butted together.
(a) is characterized by energizing the joint J with the electrofusion joint J covering the periphery of the joint (b).

The electrofusion joint used in the present invention is a known fusion splicing joint having a structure in which a nichrome wire or the like is embedded inside a joint body formed of a thermoplastic resin. The joint is a system in which the inner peripheral surface of the joint main body and the outer peripheral surface of the pipe material are melted by heating by applying electricity to the nichrome wire, and these two pipe materials and the joint main body are fused by joining the melted portions.

[0009]

[Function] When the electrofusion joint J is energized, the inner surface of the joint J and the outer surfaces of the respective pipes P1, P2 are heated and melted, and the pipes P1, P2 and the joint J are fusion-bonded and thermally expanded. Molten resin (resin whose inner surface is melted) M is filled between the abutting pipe end faces F1 and F2 without any gap.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram for explaining the procedure of an embodiment of the joining method of the present invention. First, as shown in (a), the pipe end faces F1 and F2 of the pipe members P1 and P2 to be connected are processed into a conical taper shape with an inclination with respect to the pipe center.
P2 is attached to each of the pair of clamps 1 and 2, and each pipe end is fixed in a state of being butted against each other.

Next, as shown in (b), the outer circumference of the pipe joint is covered with an electrofusion joint J, and the joint J is energized in this state. Due to this energization, the inner surface of the joint J and the outer surfaces of the pipe materials P1 and P2 are heated and melted, and as shown in (c), the joint and the pipe materials are fusion-bonded to each other and the abutted pipe end faces F1 Gap between V and F2 (V
The molten resin M that has melted the inner surface of the joint and has been thermally expanded is filled in the (valley-shaped valley portion) without any gaps, so that the pipe end faces F1 and F1
When 2 and 2 are joined together, no fine gaps will be formed on the inner surface of the joined portion. Further, the molten resin M will not be extruded to the inner surface side of the joint.

The inclination angles θ (see FIG. 1 (a)) of the respective pipe end faces F1 and F2 of the pipe materials P1 and P2 are not particularly limited, but are preferably about 30 to 45 °, for example. Further, in the above embodiments, the pipe ends of the respective pipe materials P1 and P2 are processed into a shape in which the outer peripheral surface side is inclined, but the opposite inclination, that is, the shape in which the pipe end inner peripheral side is an inclined surface is processed. However, the method of the present invention can be carried out.

[0013]

As described above, according to the fusion bonding method of the present invention, each pipe end surface of the pipe material to be connected is inclined, the pipe end portions are abutted, and the electrofusion is performed on the outer periphery of the joint portion. Since the pipe materials are joined by covering the joint and energizing the joint in this state, no beads or fine gaps are formed on the inner surface of the joint, and a good joint can be obtained. Therefore, it is possible to sufficiently deal with clean applications.

Further, according to the present invention, since the two pipe members for connection are basically fusion-bonded by the electrofusion joint, there is also an effect that a sufficient joint strength can be obtained. .

[Brief description of drawings]

FIG. 1 is a diagram illustrating a procedure of a joining method of the present invention.

FIG. 2 is a diagram for explaining a conventional example of an inner bead elimination method.

[Explanation of symbols]

 P1, P2 pipe material (thermoplastic resin molded product) F1, F2 pipe end face J electrofusion joint 1,2 clamp

Claims (1)

[Claims] 1. A method for connecting pipes formed of a thermoplastic resin by fusion bonding, in which the pipe end faces of two pipes to be connected are each inclined by a predetermined angle with respect to the center of the pipe. A method for fusion-bonding pipe materials, characterized in that the ends of these pipes are abutted, and the joints are covered with an electrofusion joint, and the joints are energized. .