JP2516996Y2 - Electrofusion fittings - Google Patents

Description

TECHNICAL FIELD The present invention relates to a pipe joint used for connecting plastic pipes, and in particular, a coiled heating wire (hereinafter referred to as a coil) is embedded inside and a current is applied to this. The present invention relates to an electrofusion joint in which a contact surface with a tube is fused by heating and melting.

2. Description of the Related Art Electrofusion joints have been recently developed as pipe joints for plastic pipes used for water and sewer pipes and gas pipes. As shown in the figure, this joint consists of a molded product with a coil embedded inside, and fusion with the pipe is performed by inserting the pipe from both sides of the joint and energizing it to heat and melt the contact surface. It has become.

Problems to be solved by the invention Electrofusion joints can be connected simply by inserting the pipes from both sides of the joint and energizing the pipes, and then heating and melting the contact surfaces of the pipe joint and the pipe as in the past. After that, compared to inserting the pipe joint into the pipe, there is an advantage that the connection work can be performed easily and quickly, the work efficiency is improved, and the connection can be performed relatively reliably. It has a problem to be solved. One of them energizes the coil to generate heat, and when the surrounding thermoplastic resin is melted, the coil is swept by the flow of the molten resin, or the coil moves due to the twisting of the coil itself, and the coil pitch becomes uneven. As a result (Fig. 8), if the pitch is not uniform, the heat generation density will also be non-uniform, resulting in short-circuiting as shown in Fig. 8 D and F, or the temperature will become too high in the small pitch area B Cause high temperature deterioration of
As indicated by C, E, and G, in a portion with a large pitch, the temperature rise is small and insufficient melting occurs, and in either case, defective melting occurs.

The present invention is to prevent the short circuit and the melting failure as described above by keeping the heat generation density uniform by keeping the pitch of the coil unchanged, so that the pitch of the coil does not change. For this purpose, the coils are connected by any one of the following connecting means (1) to (4) to be in a fixed state.

(1) As shown in FIG. 2, a plate-shaped member extending in the axial direction of the joint, having non-conductivity and heat resistance, and one side of which the coil 3 is fitted at the same pitch as the coil 3. A connecting member 2 having a groove 1 is formed, and a coil 3 is provided in each groove of the member 2.
Means for connecting the coils by fitting.

(2) As shown in FIG. 4, a rod-shaped member extending in the axial direction of the joint, having a heat-resistant connecting member 6, and a non-conductive and heat-resistant connecting member 6 provided with a coil 7. The adhesive 8 for connecting the coil 7 to the connecting member 6
Or a rod-shaped member extending in the axial direction of the joint, which is non-conductive and has heat resistance.
And an adhesive 8 having heat resistance and connecting the coil 7 to the connecting member 6, and connecting the coil 7 to the connecting member 6 via the adhesive 8.

(3) As shown in FIG. 6, means for connecting the coil 12 to the heat-meltable plastic sleeve 13 to the outer surface of the sleeve via a non-conductive and heat-resistant band-shaped adhesive which is continuous in the axial direction. As the adhesive used for connecting, for example, bisphenol type epoxy, epoxy phenol,
There are butadiene-acrylonitrile, silicone, modified silicone and the like.

Example FIG. 1 shows an example in which a non-conductive and heat-resistant connecting member 2 having a structure as shown in FIG. 2 is fitted into a coil 3 from above and below and from the front and back so that the coil does not move in the axial direction. FIG. 3 shows an electrofusion joint in which the coil 3 connected by the connecting member 2 as described above is integrally formed by insert molding.

FIG. 4 shows an example in which the connecting member 6 is applied from above and below and to the front and back of the coil 7 and is adhered and connected by a heat-resistant adhesive 8. In FIG. 5, such a coil 7 is integrally formed. 3 shows an electrofusion joint. Here, the connecting member 6 is preferably non-conductive, but may not be non-conductive as long as it is in non-contact with the coil 7 and a sufficient adhesive agent is interposed therebetween.

FIG. 6 shows an example in which a plastic sleeve 13 is fitted into the coil 12, and a heat-resistant adhesive 11 is applied to the upper, lower, front and rear portions of the coil 12, and the coil 12 is connected to the sleeve. FIG. 7 shows an electrofusion joint in which this is integrally molded. The sleeve 13 is melted and integrated at the time of insert molding.

Effect of the Invention According to the electrofusion joint of the present invention, the embedded coil is fixed so as not to move in the axial direction, and the flow may be caused by the flow of the molten resin, or the coil itself may be twisted to cause a short circuit. Since the pitch is maintained at the initial pitch, the heat generation density becomes uniform, and melting failure does not occur.

[Brief description of drawings]

1 is a sectional view of a coil connected by a connecting member, FIG. 2 is a partially enlarged view of the connecting member, FIG. 3 is a sectional view of an electrofusion joint in which the coil shown in FIG. 1 is embedded, and FIG. FIG. 5 is a cross-sectional view of the coil of the embodiment, FIG. 5 is a cross-sectional view of the electrofusion joint in which the coil shown in FIG. 4 is embedded,
FIG. 6 is a partially cutaway front view, FIG. 7 is a sectional view of an electrofusion joint in which the coil shown in FIG. 6 is embedded, and FIG. 8 is a conventional electrofusion showing a state in which plastic pipes are connected. It is sectional drawing of a joint. 1 ... Groove, 2 ... Connection member, 3, 7, 12 ... Coil 6 ... Connection member, 8, 11 ... Adhesive

Claims (1)

(57) [Scope of utility model registration request] 1. An electrofusion joint in which a coil-shaped heating wire is embedded inside, and electric current is applied to the heating wire to heat and melt the contact surface with a plastic tube to thereby fuse the electrofusion joint,
In order to prevent the heating wire from moving in the axial direction during heating and melting, the coiled heating wire is connected by any one of the following connecting means (1) to (4) to be in a fixed state. And an electrofusion joint. (1) A connecting member 2 that is a plate-shaped member that extends in the axial direction of the joint, has non-conductivity and heat resistance, and has a groove 1 into which the coil 3 fits at the same pitch as the coil 3 on one side thereof. And means for connecting the coils by fitting the coils 3 into the respective grooves of the member 2. (2) A rod-shaped member extending in the axial direction of the joint, which is composed of a heat-resistant connecting member 6 and an adhesive 8 which is non-conductive and heat-resistant and connects the coil 7 to the connecting member 6. Means for connecting the coil 7 to the connecting member 6 via the adhesive 8. (3) A rod-shaped member that extends in the axial direction of the joint, and is composed of a non-conductive and heat-resistant connecting member 6 and an adhesive 8 that has heat resistance and connects the coil 7 to the connecting member 6. Means for connecting the coil 7 to the connecting member 6 via the adhesive 8. (4) Coil 12 on heat-meltable plastic sleeve 13
Means for connecting the two via an adhesive, which is non-conductive and has heat resistance and which is continuous in the axial direction.