JPH0118317B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for joining joints of ductile cast iron pipes, steel pipes, plastic pipes, etc.

For slip-on type pipe fittings, when joining the fitting, generally after attaching a sealing material to the socket,
Insert the socket into the socket. This sealing material is compressed when the socket is inserted to ensure a secure seal, but the sealing material must be There is a limit to the range that can be compressed, that is, the inner diameter before compression. Therefore, as shown in FIG. 5, when the socket and socket are deformed into elliptical shapes due to bending in the direction of arrow P in the joint, the socket inner surface 11 and socket outer surface 12 that occur in the direction perpendicular to the bending direction. There is a problem in that the large gap δ between them cannot be sufficiently closed by the sealing material, resulting in insufficient sealing function. The above problem is particularly severe in the case of pipes with large diameters.

The present invention proposes a joint joining method that can highly compress the sealing material and ensure reliable sealing even when bending or the like occurs. Therefore, the present invention provides a socket formed at the end of the first pipe and a second pipe.
a socket formed at the end of the tube and inserted into the interior of the socket; and an annular recess formed on the inner surface of the socket, and between the annular recess and the outer surface of the socket. A method for joining a pipe joint having an annular sealing material that is compressed by compressing the pipe, the insertion port being pressurized from the outside to reduce its diameter, and the sealing material being placed in an annular groove of the socket. The socket is inserted in a reduced diameter state into the socket where the sealing material is placed, and the socket is restored after insertion. Embodiments of the present invention will be described below based on the drawings.

FIGS. 1 and 2 show an example of a pipe joint to which the present invention is applied, where 1 is a socket and 2 is an insertion port. An annular recess 3 is provided on the inner surface of the socket 1, and a rubber annular seal 4 is disposed within the annular recess 3. The sealing material 4 has, for example, a circular cross-sectional shape in its natural state before insertion of the insertion port 2, and its inner diameter d is formed to be sufficiently smaller than the outer diameter D of the insertion port 2.

To explain the method of joining the joint, first, a sealing material 4 is placed in the annular recess 3 of the socket 1, and the socket 2 is compressed from the outside using an appropriate drawing device to reduce its diameter. Then, the socket 2 is removed from the diaphragm, and while the diameter is in the reduced state until it is restored, the socket 2 is inserted into the socket 1 as shown by the dashed line in FIG. and,
By leaving it as it is, the insertion port 2 will return to its original diameter due to the elasticity of the material (as shown by the two-dot chain line in Figure 2).
and the bonding is completed. Note that it is necessary to appropriately select the material of the socket 2 so that the diameter of the socket 2 can be maintained in a reduced diameter state until the insertion of the socket 2 into the socket 1 is completed.

In this way, since the socket 2 is inserted into the socket 1 in a reduced diameter state, the socket 2 can be inserted even if the sealing material 4 has a sufficiently small inner diameter, and the socket 2 can be inserted into the socket 1 after insertion. By restoring, the sealing material 4 can be highly compressed and high watertightness can be obtained. In addition, even if the gap between the socket 1 and the socket 2 becomes large due to bending of the joint and elliptical deformation, the seal material 4 can be made with a small inner diameter before compression, so the seal The restoration range of the material 4 is large, so that sealing performance can be maintained. Depending on the purpose, the diameter of the insertion port 2 may be reduced slightly, or it may be reduced significantly as shown in the figure.

In the above embodiment, the socket 2 was inserted into the socket 1 after being removed from the squeezing device, but the root portion of the socket 2, that is, the portion of the socket 2 exposed from the socket 1 was pressurized by the squeezing device. If the diameter is reduced so that the diameter of the socket 2 is reduced over the entirety thereof, the socket 2 can be inserted into the socket 1 with the diaphragm attached.
In this case, the insertion port 2 may be made of a material that instantly restores its original state when the pressure is removed.

The method of the present invention is not limited to the pipe joint shown in FIG. 1, but can also be applied to the pipe joints shown in FIGS. 3 and 4. 3 shows an annular protrusion 5 on the inner surface of the socket 1 that engages a recess on the outer periphery of the sealing material 4, and FIG. This is to fit the two.

As explained above, according to the method of the present invention, the insertion port is inserted into the socket in a reduced diameter state and then restored, so that high compression can be achieved by using a sealing material with a small inner diameter. Therefore, the sealing performance is improved and the sealing performance can be maintained even if the joint portion is bent.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an example of a pipe fitting to which the method of the present invention is applied, Fig. 2 is an explanatory diagram of the joining operation of the pipe fitting, and Figs. 3 and 4 are pipe fittings to which the method of the present invention is applied. FIG. 5 is an explanatory diagram showing a cross section of the joint in a bent state. 1... Socket, 2... Socket, 3... Annular recess, 4
...Sealing material.

Claims (1)

[Claims] 1 A socket formed at the end of the first pipe, an insertion port formed at the end of the second pipe and inserted into the socket, and an annular shaped socket formed on the inner surface of the socket. A method for joining a pipe joint having an annular sealing material disposed in a recess and compressed between the annular recess and an outer surface of the insertion port, the method comprising compressing the insertion port from the outer surface to reduce its diameter. At the same time, the sealing material is arranged in the annular groove of the socket, the socket is inserted in a reduced diameter state into the socket where the sealing material is arranged, and the socket is restored after insertion. How to join pipe fittings.