JP2021060057A - Structure and method for connecting pipe joint to pipe - Google Patents

Abstract

To connect a joint to a pipe by reliably and firmly coupling a connection port of the pipe joint having irregularities at an outer peripheral surface to an end of the pipe.SOLUTION: A structure for connecting a pipe joint to a pipe includes steps of connecting a pipe to a joint by press fitting an inner peripheral surface of the pipe to an outer peripheral surface of a connection port of the pipe joint; and fixing the connection of the pipe by press fitting a tightening ring with a length from a bottom part to a tip of the connection port of the pipe joint at an outer peripheral surface of the pipe, where thicknesses of both members are set so that a wall thickness (Tp) of the pipe and a wall thickness (Tw) of the tightening ring satisfy the relation of (1.2≤Tp/Tw≤9.0).SELECTED DRAWING: Figure 5

Description

The present invention relates to a structure for connecting a pipe to a pipe joint and a method thereof.

Cross-linked polyethylene pipe, which is a typical resin pipe, is made of a chemically stable material, is lightweight and flexible, is easy to transport, and has excellent workability in piping work at the construction site. It is widely used as a conduit for transporting liquids and gases in equipment for heating and cooling, air conditioning, and water supply and drainage.

When connecting a resin pipe to a pipe joint of another pipe, the diameter of the end opening of the pipe is reversibly expanded so as to be larger than the outer diameter of the connection port of the connecting pipe or pipe joint at atmospheric temperature. If the end of the pipe whose diameter has been expanded is fitted to the connection port in that state, the expanded end can be firmly sealed and bonded to the outer peripheral surface of the connection port by automatic return deformation at atmospheric temperature. It is known that it can be done (see, for example, Patent Document 1).

Special Table 6-509994

In the piping of water supply and drainage equipment, a joint (hereinafter, simply "joint" or simply "joint" or (Also referred to as "pipe fitting") may be used.
As a method of connecting the conduit to the connection port of the joint, there is a method of fitting the open end of the conduit to the connection port and then winding a hose band around the outer peripheral surface of the conduit to fix the conduit.

When such a method is used, the stress is concentrated in a line shape on the outer peripheral surface of the pipe by tightening the string-shaped or strip-shaped hose band, and this stress is combined with the fact that there is a step on the outer peripheral surface of the connection port. Concentration may hinder the adhesion between the inner and outer peripheral surfaces of the pipe and the connection port, create a gap, and leak the medium flowing through the conduit.
Further, the amount of force for tightening the hose band varies depending on the construction worker, and if the tightening is loose, the hose band may come off and the pipe fixed to the connection port may come off from the connection port.

In view of such problems of the prior art, the present invention makes it possible to securely and firmly connect the end portion of the pipe to the connection port of the joint having irregularities on the outer peripheral surface. Make it an issue.

As a means for solving the above-mentioned problems, instead of the hose band, a tightening ring made of synthetic resin is attached to the outer peripheral surface of the pipe in advance, and in that state, the diameter of the end opening of the pipe is expanded to connect the joint. It is conceivable to fit it in. By doing so, there is no variation in tightening by the construction worker, and the tightening ring does not come off. However, when the tightening ring is narrow, by attaching it, a line shape is formed on the outer peripheral surface of the pipe. The stress is still concentrated in. Stress concentration can be avoided by using a tightening ring with a sufficient length in the axial direction, but depending on the thickness of the tightening ring, it becomes difficult to increase the diameter of the pipe end opening, which hinders the connection operation to the joint. Come.

Therefore, the present invention employs a connection mode in which a tightening ring is attached to the outer peripheral surface of the pipe connected to the connection port of the joint, and the length of the tightening ring and the ratio of the wall thickness of the pipe and the tightening ring are appropriately adjusted. By doing so, the end of the pipe is securely and firmly connected to the connection port of the joint by a smooth connection operation.

That is, the present invention relates to a pipe joint and a pipe connection structure.
The pipe is connected by pressing the inner peripheral surface to the outer peripheral surface of the connection port protruding from the pipe joint, and is the outer peripheral surface thereof and is the root portion of the connection port of the pipe joint inserted into the pipe. A tightening ring is pressed into the area extending from the tip to the tip and fixed to the connection port.
The wall thickness (Tp) of the pipe and the wall thickness (Tw) of the tightening ring have the following relationship.
(1.2 ≤ Tp / Tw ≤ 9.0)

According to this, since the tightening ring is mounted on the outer peripheral surface of the pipe over the area from the root to the tip of the connection port of the pipe joint inserted into the pipe, the inner peripheral surface of the pipe is mounted. The pipe can be tightened and fixed to the connection port while maintaining the close contact strength of the connection port evenly.
If the ratio of the wall thickness (Tp) of the pipe to the wall thickness (Tw) of the tightening ring is 1.2 or more (1.2 ≤ Tp / Tw) with the pipe fixed to the pipe joint, the tightening ring There is no problem in the operation of connecting the pipe with the attached to the connection port of the joint.
On the other hand, when the wall thickness ratio is larger than 9.0 (Tp / Tw ≦ 9.0), that is, when the thickness of the outer pipe is 1/9 or less of the pipe, a sufficient tightening force to the pipe is obtained. I can't do it.
The wall thickness (Tw) of the tightening ring referred to here is the root portion side of the region where the tightening ring is press-fitted over the region from the root portion to the tip portion of the connection port of the pipe joint. It refers to the wall thickness of the part attached to.

The connection structure is effective in a mode in which a pipe is connected to a pipe joint in which a plurality of inclined stepped portions having an enlarged diameter from the tip end side to the root portion side are formed on the outer peripheral surface of the connection port. It can also be applied to the connection between the pipe and the pipe in a form other than the pipe joint.

The pipe joint preferably used in the present invention has a connection port to which the pipe is connected, in which the outer diameter is formed in a constricted shape from the root side to the tip side. In the present invention, a pipe having an inner diameter of an end opening smaller than the outer diameter of the connection port of the pipe joint is provided to such a pipe joint, and the connection port of the pipe joint is provided inside while expanding the diameter of the end opening. It can be applied to the connection structure of pipe joints and pipes that are press-fitted and connected.

In the connection structure, the outer diameter of the pipe (φpo) and the inner diameter of the tightening ring (φwi) have the following relationship.
(Φpo ≧ φwi)
Further, in the connection structure, the inner diameter (φpi) of the pipe is smaller than the maximum outer diameter (φco) of the connection port of the pipe joint, and the diameter of the inner diameter of the end opening of the pipe is expanded to 3% or more. , A pipe is connected to the connection port.
If the diameter expansion rate is 3% or more, the inner peripheral surface of the pipe will be pressed against the outer peripheral surface of the connection port with sufficient strength due to the automatic return deformation after connecting to the connection port of the pipe joint, and high sealing performance will be exhibited. can do.

Further, in the connection structure, the molding material of the pipe and the tightening ring has physical properties such that the tensile stress at 10% elongation based on the stress-strain curve is 10 MPa or more and the elongation (strain) at break is 300% or more. Is preferable.
That is, FIG. 6 shows the stress-strain curve (SSC) of the pipe and the tightening ring, and the point A in the figure shows the tensile stress at the time of stretching by about 10%.
That is, the point A can be said to be the value of the tensile stress applied when the diameter expansion ratio of the pipe or the tightening ring is about 10%, and the larger this value, the higher the tightening force of the joint.
From this point of view, the value of tensile stress at 10% elongation based on the stress-strain curve is preferably 10 MPa or more, more preferably 15 MPa or more, and even more preferably 20 MPa or more.
Point B in the figure is a point showing the elongation at break of the pipe or the tightening ring.
From the viewpoint of preferably expanding the diameter of the pipe or tightening ring and preferably contracting it after inserting the joint, the elongation at break is preferably 300% or more, more preferably 350% or more, and 400% or more. Is more preferable.

The connection structure between the pipe joint and the pipe uses a tightening ring having the above-mentioned wall thickness ratio and length with respect to the wall thickness of the pipe, and the diameter of the end opening of the tightening ring is enlarged to press the outer peripheral surface of the pipe. Construction is possible by a method having a step of mounting the pipe and a step of mounting the tightening ring on the outer peripheral surface of the connection port of the pipe joint by expanding the diameter of the end opening of the pipe mounted on the outer peripheral surface. Is.
In this case, if necessary, the tightening ring can heat the end opening of the pipe mounted on the outer peripheral surface and connect to the connection port of the joint.

It is a figure which shows the pipe and the tightening ring used in one Embodiment of this invention by breaking a part. It is a figure which showed an example of the process of expanding the diameter of the end opening of the tightening ring of FIG. It is sectional drawing in the state which the tightening ring was attached to the outer peripheral surface of the pipe of FIG. It is a figure which showed the pipe of FIG. It is sectional drawing of the state in which the pipe of FIG. It is a stress-strain curve of a pipe and a tightening ring of FIG.

Hereinafter, an embodiment of the connection structure between the pipe joint and the pipe of the present invention will be described with reference to the drawings. The present invention is not limited to this embodiment.

The illustrated form is a mode in which a pipe made of synthetic resin is connected to a joint made of synthetic resin which is a pipe joint. In the figure, reference numeral 1 is a pipe, 2 is a tightening ring, and 3 is a pipe joint.

Both the pipe 1 and the tightening ring 2 are cross-linked polyethylene pipes, and have the physical characteristics defined by the stress-strain curve shown in FIG.

A pipe 1 having an inner diameter (φpi) smaller than the maximum outer diameter (φco) of the connection port 31 of the pipe joint 3 is used, and the inner diameter of the end opening of the pipe 1 is expanded by 3% or more. The diameter is increased so that it can be connected to the connection port 31.

Further, as the tightening ring 2, one having an inner diameter (φwi) equal to or smaller than the outer diameter (φpo) of the pipe 1 (φpo ≧ φwi) is used. Further, the tightening ring 2 is used having a length in the axial length direction of at least a length extending from the root portion to the tip portion of the connection port 31 of the pipe joint 3.

To connect the pipe 1 to the pipe joint 3, first, the tightening ring 2 is attached to the outer peripheral surface of the pipe 1, and then the pipe 1 to which the tightening ring 2 is attached is connected to the connection port 31 of the pipe joint 3. Is done by.

That is, first, as shown in FIG. 2, the inner diameter of the end opening of the tightening ring 2 is expanded by pushing the diameter-expanding tool 4 into the end opening on one side of the tightening ring 2.
When the inner diameter is expanded to about half the depth in the length direction of the tightening ring 2, the expanded end opening side is put on the outer peripheral surface of the end portion on one side of the pipe 1 and pushed in, as shown in FIG. In addition, the tightening ring 2 is mounted on the outer peripheral surface of the pipe 1. The operation of mounting the tightening ring 2 on the pipe 1 with a rubber hammer is performed by covering the outer peripheral surface of the end portion on one side of the pipe 1 with the enlarged end opening side of the tightening ring 2 on the other side of the tightening ring 2. This can be done by hitting the end with a rubber hammer and pushing it in.
As another method, the diameter of the tightening ring 2 in all the length directions may be increased by a diameter-expanding tool, and immediately after that, the tightening ring 2 may be put on the outer peripheral surface of the pipe 1 and pushed in.
In either method, a gap may be formed between the tightening ring 2 and the pipe 1 immediately after the diameter is expanded, but the pipe 1 is appropriately tightened as the tightening ring 2 contracts over time.

Next, the diameter of the pipe 1 on which the tightening ring 2 is mounted on the outer peripheral surface shown in FIG. 3 is expanded, and the pipe 1 is mounted on the outer peripheral surface of the connection port 31 of the pipe joint 3.
If it is difficult to attach the joint, the inner diameter of the pipe 1 to which the tightening ring 2 is attached may be increased, and in that case, the diameter-expanding tool can be used. For example, the diameter-expanding tool can be used for the operation of increasing the inner diameter of the pipe 1. For example, with the connection port 31 of the pipe joint 3 inserted into the end opening of the expanded pipe 1, the other end of the pipe joint 3 is hit with a rubber hammer to push the connection port 31 into the pipe 1. By pushing the pipe joint 3 toward the pipe 1 side using a pushing tool such as a smoother, the end portion of the pipe 1 can be mounted on the outer peripheral surface of the connection port 31. At this time, by heating the end opening of the pipe 1 as necessary, the operation of pushing the connection port 31 of the pipe joint 3 into the pipe 1 can be smoothly performed.

[Example 1]
A pipe made of cross-linked polyethylene with an outer diameter of φpo of 24.2 mm and an inner diameter of φpi of 16.2 mm, and a pipe made of cross-linked polyethylene with an outer diameter of φwo of 27.0 mm and an inner diameter of φwi of 20.5 mm and an axial length of 30 mm. Prepared the tightening ring.
A tightening ring was fitted around the outer periphery of the end of the pipe, and this was connected to a pipe joint made of synthetic resin having an outer diameter of 16.6 mm at the tip of the connection port and an outer diameter of 18.2 mm at the root. The length of the connection port of the pipe joint is 26 mm.

The connection to the pipe joint was made as follows.
First, the end opening of the tightening ring is widened using a diameter-expanding tool, then the pipe is inserted into the tightening ring, and the other end of the tightening ring is closed until the entire tightening ring overlaps the outer peripheral surface of the pipe. I hit it with a rubber hammer and pushed it into the outer peripheral surface of the pipe.
Next, after expanding the diameter of the end of the pipe to which the tightening ring is attached using a diameter expansion tool, the expanded portion of the pipe is heated at 80 ° C. for 30 seconds, and immediately after heating, the pipe joint is heated with a rubber hammer. I hit it and pushed the connection port into the pipe to fix it.

Measure the wall thickness (Tp) of the pipe that is connected and fixed to the connection port of the pipe joint and the wall thickness (Tw) of the tightening ring that tightens the outer peripheral surface of this pipe, and measure the ratio (Tp / Tw). I asked. The results are shown in Table 1.
Table 1 also shows the results of evaluation of the ease of inserting the pipe and the tightening force.

[Example 2]
Connection of a pipe to a pipe joint in the same manner as in Example 1 except that a cross-linked polyethylene tightening ring having an outer diameter of φwo of 21.5 mm and an inner diameter of φwi of 16.2 mm and an axial length of 30 mm is used. And the wall thickness (Tp, Tw) was measured and evaluated.

[Example 3]
Connection of a pipe to a pipe joint in the same manner as in Example 1 except that a cross-linked polyethylene tightening ring having an outer diameter φwo of 14.6 mm and an inner diameter φwi of 9.8 mm and an axial length of 30 mm is used. And the wall thickness (Tp, Tw) was measured and evaluated.

[Example 4]
Connection of a pipe to a pipe joint in the same manner as in Example 1 except that a cross-linked polyethylene tightening ring having an outer diameter φwo of 17.0 mm and an inner diameter φwi of 12.6 mm and an axial length of 30 mm is used. And the wall thickness (Tp, Tw) was measured and evaluated.

[Example 5]
Connection of a pipe to a pipe joint in the same manner as in Example 1 except that a cross-linked polyethylene tightening ring having an outer diameter of φwo of 13.0 mm and an inner diameter of φwi of 9.8 mm and an axial length of 30 mm is used. And the wall thickness (Tp, Tw) was measured and evaluated.

[Comparative Example 1]
A cross-linked polyethylene pipe having an outer diameter of 24.2 mm and an inner diameter of φpi of 16.2 mm was connected to the pipe joint of Example 1 without using a tightening ring. The connection was made by expanding the diameter of the end opening and heating the enlarged diameter portion in the same manner as in the embodiment.
At this time, the ease of inserting the pipe and the tightening force were evaluated.

[Comparative Example 2]
Connection of a pipe to a pipe joint in the same manner as in Example 1 except that a tightening ring made of cross-linked polyethylene having an outer diameter φwo of 13.0 mm and an inner diameter φwi of 11.0 mm and an axial length of 30 mm is used. And the wall thickness (Tp, Tw) was measured and evaluated.

[Comparative Example 3]
Connection of a pipe to a pipe joint in the same manner as in Example 1 except that a cross-linked polyethylene tightening ring having an outer diameter of φwo of 24.2 mm and an inner diameter of φwi of 16.2 mm and an axial length of 30 mm is used. And the wall thickness (Tp, Tw) was measured and evaluated.

The tightening force and ease of inserting the pipe were evaluated according to the following criteria.
(Tightening force)
Water pressure was applied to the pipe to which the tightening ring was attached, and the pipe that was broken without the joint coming off was marked with ◯, and the pipe with the fitting removed was marked with x.
(Easy to insert pipe)
After heating the pipe with the tightening ring at 80 ° C for 30 seconds, the ease of fitting when hitting the pipe joint with a hammer is ○ for those that can be fitted to the root without problems, and × for those that do not fit at all. And said.

In Examples 1 to 5, the ratio (Tp / Tw) of the wall thickness (Tp) of the pipe to the wall thickness (Tw) of the tightening ring is (1.2 ≦ Tp /) in a state of being connected to and fixed to the pipe joint. Within the range of Tw ≤ 9.0), the pipe is fixed to the pipe joint with sufficient tightening force, and in terms of ease of inserting the pipe into the connection port of the pipe joint, to the base of the connection port. I was able to fit the pipe firmly.
On the other hand, in Comparative Example 1 in which the tightening ring is not used, there is no problem in fitting the pipe to the connection port of the pipe joint, but the tightening force is insufficient.
Further, in Comparative Example 2, the wall thickness ratio (Tp / Tw) is 10.0, and it is confirmed that the tightening force of the pipe is insufficient if the wall thickness ratio with the pipe is too large even if the tightening ring is used. Was done.
In Comparative Example 3, the pipe was not inserted in the connection port of the pipe joint and could not be connected. Therefore, it was not possible to evaluate the tightening force applied to the pipe by applying water pressure. At this time (the state where the pipe cannot be connected to the pipe joint), the wall thickness ratio (Tp / Tw) of the pipe 1 and the tightening ring 2 is 1.1, and if the wall thickness ratio is too small, the pipe is connected to the pipe joint. It was confirmed that it could not be done or that the connection operation became difficult.

The illustrated pipe 1, tightening ring 2, and pipe joint 3 show an example of the present invention. The present invention is not limited to the exemplary form, and can be configured in other appropriate forms.

1 Pipe, 2 Tightening ring, 3 Pipe fitting, 31 Connection port, 4 Diameter expansion tool

Claims (7)

In the connection structure of pipe fittings and pipes
The pipe is connected by pressing the inner peripheral surface to the outer peripheral surface of the connection port protruding from the pipe joint, and is the outer peripheral surface thereof and is the root portion of the connection port of the pipe joint inserted into the pipe. A tightening ring is pressed into the area extending from the tip to the tip and fixed to the connection port.
A connection structure between a pipe joint and a pipe, wherein the wall thickness (Tp) of the pipe and the wall thickness (Tw) of the tightening ring have the following relationship.
(1.2 ≤ Tp / Tw ≤ 9.0) The connection structure between a pipe joint and a pipe according to claim 1, wherein the pipe joint is formed with a plurality of inclined stepped portions whose diameters are expanded from the tip end side to the root portion side on the outer peripheral surface of the connection port. The connection structure between a pipe joint and a pipe according to claim 1 or 2, wherein the outer diameter (φpo) of the pipe and the inner diameter (φwi) of the tightening ring have the following relationship.
(Φpo ≧ φwi) The inner diameter (φpi) of the pipe is smaller than the maximum outer diameter (φco) of the connection port of the pipe joint, and the diameter of the inner diameter of the end opening of the pipe is expanded to 3% or more, and the pipe is inserted into the connection port. The connection structure between a pipe joint and a pipe according to any one of claims 1 to 3, wherein the pipe joint and the pipe are connected. Claim 1 that the molding material for a pipe and a tightening ring has a physical property such that the tensile stress at 10% elongation based on the stress-strain curve is 10 MPa or more and the elongation (strain) at fracture is 300% or more. The connection structure of the pipe joint and the pipe according to any one of 4 to 4. In the method of connecting pipe fittings and cross-linked polyethylene pipes,
A tubular tightening ring made of cross-linked polyethylene with a wall thickness (Tw) having the following relationship with a pipe with a wall thickness (Tp), and the length in the axial length direction is at least from the root of the connection port of the pipe joint. The process of expanding the diameter of the end opening of the tightening ring having a length extending to the tip and mounting it on the outer peripheral surface of the pipe with a cross-linked polyethylene.
A step of expanding the diameter of the end opening of the pipe to which the tightening ring is mounted on the outer peripheral surface and mounting the tightening ring on the outer peripheral surface of the connection port of the pipe joint.
How to connect pipe fittings and pipes.
(1.2 ≤ Tp / Tw ≤ 9.0) The method for connecting a pipe joint and a pipe according to claim 6, wherein the tightening ring heats the end opening of the pipe mounted on the outer peripheral surface and connects to the connection port of the joint.

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