JPH067269Y2 - Connection structure between plug-in joint and pipe end - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a connection structure between an insertion joint and an end portion (hereinafter, referred to as a pipe end) of a plastic pipe for gas or water.

[Conventional technology]

Insert a pipe end such as a polyethylene pipe or polybutene pipe into a joint in which a rubber gasket and retaining ring are held in a tubular joint body, and seal the gap between the outer surface of the pipe end and the joint body with a rubber gasket to ensure airtightness or liquid sealing. When making a tight seal, the sealing performance depends on the presence or absence of scratches on the outer surface of the pipe end and the surface pressure of the rubber gasket against the pipe end and the joint body. That is, if there is a scratch on the outer surface of the tube end, good sealing performance is not maintained even if the surface pressure is increased depending on the degree of the scratch, and if the surface pressure is too low, the outer surface of the tube end may be an intact smooth surface. Sufficient sealing performance is not exhibited. Also, if the surface pressure is too large, sufficient sealing performance can be maintained, but since the size of the surface pressure is related to the compression rate of the rubber gasket, it is in a natural state (non-compressed state) to obtain a large surface pressure. It is necessary to keep the inner diameter of the rubber gasket small at the time.In doing so, when inserting the pipe end into the joint, the rubber gasket interferes with the insertion resistance of the pipe end and the workability is increased. It causes a large decrease.

Therefore, the joints shown in FIGS. 5 and 6 have been conventionally proposed.

The joint shown in FIG. 5 is a general mechanical joint, and a rubber gasket 102 is housed in a receiving port 101 of a tubular joint body 100, and a rubber ring 102 is inserted through a retainer 104 by a push ring 103 screwed into the joint body 100. Rubber gasket 1 by axially pressing (compressing)
02 is pressed against the outer surface of the pipe end 200 and the joint body 101, and the retaining ring 106 is sandwiched between the taper surface 105 of the push ring 103 and the pipe end 200, and the retaining ring 106 is wedged to form the retaining ring 106. It is a structure to make it bite into 200. The tube end 200 has a cylindrical stiffener 2
01 is fitted, and the rubber gasket 102 and the retaining ring 1 are reinforced by the reinforcing effect of the stiffener 201.
The tube end 200 is prevented from being deformed by tightening 06.

The joint shown in FIG. 6 is a so-called plug-in joint, and has a tubular joint body 11
The rubber gasket 113 and the retaining ring 114 are housed in the two annular grooves 111 and 112 formed in the inner peripheral portion of the 0, and the rubber gasket 113 is sandwiched by the pipe end 200 and the joint body 110 inserted into the joint body 110. The rubber gasket 1 is pressed by the reaction force due to the restoring property of the rubber gasket 113.
13 is pressed against the joint body 110 and the outer surface of the pipe end 200, and a retaining ring 114 is sandwiched between the pipe end 200 and the tapered surface 115 of the annular groove 112, and the retaining ring 114 is wedged. Is configured to be bitten into the pipe end 200.

[Problems to be solved by the device]

According to the joint of FIG. 5, the amount of deformation of the rubber gasket 102 in the radial direction increases by increasing the screwing length of the push ring 103, so that the outer diameter of the pipe end 200 is the inner diameter of the rubber gasket 102 in the uncompressed state. Even if the size is smaller than the proper size set based on the size, if the outer diameter size is within the tolerance range, the surface pressure between the rubber gasket 102 and the outer surface of the pipe end 200 is increased to the extent that sufficient sealing performance can be maintained. It is possible. However, as compared with the joint shown in FIG. 6, extra parts such as the push ring 103 and the retainer 104 are required, and at the same time, the joint main body 100 needs to be formed with a screw, resulting in high cost and connection of the pipe end 200. There is a drawback that the work becomes complicated. Also, the push ring 10
There is a drawback that a situation such that sufficient sealing property cannot be obtained due to insufficient tightening of item 3 is likely to occur.

On the other hand, in the joint of FIG. 6, the rubber gasket 113
Since the compression rate of is determined by the diameter dimension of the annular groove 111, the diameter dimension of the pipe end 200, and the inner diameter dimension and wall thickness of the rubber gasket 113 in the non-compressed state, the workability when inserting the pipe end 200 is reduced. In order to prevent it and to obtain a surface pressure that can maintain a sufficient sealing property, it is required to manage those dimensions with high accuracy and appropriately.

However, since the polyethylene polyethylene pipe for gas specified in JIS K6774 has a relatively large tolerance range for outer diameter and wall thickness, even if the outer diameter is accurately set to the standard dimension, the inner diameter Are not necessarily the same for each plastic tube. For it,
A stiffener 201 having the same outer diameter is used for plastic pipes having the same outer diameter as the standard dimension, and the outer diameter of the stiffener 201 is accurately set in terms of its manufacturing technology.

Therefore, when the stiffeners 201 having the same outer diameter dimension are fitted to the ends of different plastic tubes having the same outer diameter standard dimension, the thick stiffener tube having the wall thickness dimension t ₁ shown in FIG. Becomes the state where the stiffener 201 is press-fitted, the tube end 200 swells, and the outer diameter dimension d ₁ of the tube end 200 becomes larger than the initial outer diameter dimension d. In such a pipe end 200, there is a problem that the rubber gasket 113 becomes a hindrance when it is inserted into the joint of FIG. On the other hand, with respect to the thin plastic pipe having the wall thickness t ₂ shown in FIG. 8, the stiffener 201 is loosely fitted, and a slight clearance δ is generated between the stiffener 201 and the inner surface of the pipe end 200. When such a pipe end 200 (the diameter of the outer surface is d) is inserted into the joint of FIG. 6 and connected, the pipe end 200 that receives the surface pressure of the rubber gasket 111 is reduced in diameter by a clearance δ mainly due to a stress relaxation phenomenon over time. If so, there is a problem that the surface pressure of the rubber gasket 111 is insufficient and sufficient sealing performance cannot be maintained.

In addition, the surface of the pipe end 200 may be damaged during the actual piping work. When the damaged pipe end 200 is inserted into the joint and connected, even if the rubber gasket 113 is pressed against the damaged portion, it is damaged. Depending on the degree, the sufficient sealing property may not be obtained, and in addition, there is a problem that the sealing property further deteriorates when the pipe end 200 has a reduced diameter due to a stress relaxation phenomenon or the like.

In view of the above problems, the present invention has been made on the basis of using the above-mentioned plug-in joint which has the advantages that the number of parts is small and connection work is easy, and the pipe end into which the stiffener is press-fitted is inserted into the joint. By doing so, although a connection state in which the diameter of the pipe end does not decrease can be obtained, the insertion resistance to the joint does not increase, and the surface pressure of the elastic seal member such as the rubber gasket is appropriately maintained for a long period of time. An object is to provide a connection structure between a plug joint and a pipe end.

[Means for Solving the Problems]

The connection structure between the insertion joint and the pipe end according to the present invention has a tubular stiffener at the end of the plastic pipe inserted into the insertion joint in which the elastic seal member and the retaining ring are held by the tubular joint body. The outer surface of the end of the plastic pipe is pressed concentrically with the stiffener with the stiffener pressed in, and the diameter dimension set based on the inner diameter dimension of the elastic seal member in the non-compressed state. The elastic seal member is pinched by the outer surface of the end of the plastic pipe and the joint body, and the plastic pipe is retained by the retaining ring. To do.

[Action]

According to this configuration, since the outer surface of the pipe end is a smooth surface that is cut with the stiffener pressed in, if the surface of the pipe end is damaged, the damage is removed by cutting, and Since there is no clearance between the pipe end and the stiffener, the pipe end will not contract due to the surface pressure of the elastic seal member such as a rubber gasket, and the outer diameter of the pipe end will be stable even after long-term use. Become. In addition, since the diameter of the outer surface of the pipe end is set with reference to the inner diameter of the elastic seal member, it is stable and stable even for pipe ends with different compression rates of the elastic seal member. The sealability is maintained, and the insertion resistance when inserting the pipe end into the joint body does not increase.

〔Example〕

FIG. 1 shows a plug joint A and a pipe end 20 according to an embodiment of the present invention.
The connection state with 0 is shown. The structure of the insertion joint A is the same as that of the insertion joint described in FIG. 6, 1 is a joint body, 2 and 3 are annular grooves, 4 is an elastic seal member made of a rubber gasket, 5 is a retaining ring, and 6 is an annular shape. The elastic seal member 4 is compressed by the pipe end 200 inserted into the joint body 1 and the joint body 1, which is the tapered surface of the groove 2, and the elastic seal member 4 is moved by the reaction force due to the resilience of the elastic seal member 4. 1 and the outer surface of the pipe end 200 with a predetermined surface pressure.
Further, the retaining ring 5 is sandwiched between the pipe end 200 and the tapered surface 6, and the wedge action associated therewith causes the retaining ring 5 to bite into the pipe end 200 to retain the pipe end 200. .

Here, the stiffener 201 is press-fitted into the tube end 200, and the outer surface 202 of the tube end 200 is a smooth surface concentrically cut while the stiffener 201 is press-fitted. Moreover, the pipe end 20 shown in FIG. 3 and FIG.
The diameter dimension d ₂ of the outer surface 202 of 0 is defined based on the inner diameter dimension of the elastic seal member 4 in the non-compressed state. Specifically, when the pipe end 200 is inserted into the elastic seal member 4, the elastic seal member 4 is compressed and deformed until a constant compression rate is reached, and the elastic seal member 4 has an appropriate surface pressure and thus the outer surface 202 of the pipe end 200. The diameter dimension d ₂ is set so as to press against. If the diameter dimension d ₂ of the outer surface 202 of the pipe end 200 is determined as such, when inserting the pipe end 200 into the joint body 1, the elastic seal member 4 interferes with the insertion resistance and the workability is increased. It does not cause a decline.

According to this structure, the surface pressure of the elastic seal member 4 is reduced to the pipe end 20.
Stiffener 201 and pipe end 200
Since there is no clearance between the pipe end 200 and the pipe end 200, there is no possibility that the diameter of the pipe end 200 is reduced and the sealing performance is deteriorated. Moreover, the outer diameter dimension d ₂ of the tube end 200 is set to be constant regardless of variations in the outer diameter dimension d and the wall thickness dimension t of different plastic tubes within the tolerance range. The compressibility of the elastic seal member 4 does not fluctuate due to the plastic pipe, and as a result, the surface pressure is properly set without fluctuation, and stable and good sealing performance is maintained for a long period of time. Further, since the outer surface of the pipe end 200 is a smooth surface that has been cut, even if the outer surface before cutting is scratched, the scratch is removed by cutting, and the elastic seal member 4 has a scratch-free pipe end. The outer surface of 200 is pressed to maintain a good sealing property. Regarding the polyethylene pipe for gas, when the depth of the scratch on the outer surface of the pipe end 200 exceeds 20% of the wall thickness t of the pipe end 200, the performance deteriorates, but the scratch is shallower than that. If it is only marked, it may be used for piping. However, the damage may make the sealing property unstable. In the present invention, such scratches are removed by cutting. Therefore, it is desirable that the cutting width a shown in FIGS. 3 and 4 be made within a range not exceeding 20% of the wall thickness t.

FIG. 2 shows a tool B for cutting the outer surface of the pipe end 200. This tool includes a guide rod 11 that is inserted into a stiffener 201 press-fitted into a pipe end 200 so as to be rotatable and slidable without rattling, an arm 12 provided on the guide rod 11, and a blade attached to the tip of the arm 12. 13 and is attached to, for example, the electric power tool C. Then, while the electric tool C is started to rotate the blade 13, the stiffener 201 is used instead of the bush of the guide rod 11 to cut the outer surface of the pipe end 200.
High precision cutting is possible.

3 and 4, the stiffeners 201 having the same outer diameter dimension are press-fitted into the two types of tube ends 200 having the same outer diameter dimension d and different wall thickness dimensions t, and the outer surface of the tube end 200 is fixed in that state. An example is shown in which the stiffener 201 is cut concentrically and the diameter dimension d ₂ thereof is appropriately set with reference to the inner diameter dimension of the elastic seal member 4 (see FIG. 1) in the non-compressed state. In this case, when the diameter dimension d ₂ of the outer surface 202 of the pipe end 200 after cutting becomes smaller than the diameter dimension d of the outer surface of the original pipe end 200 as shown in FIG. 4, the joint body 1 of FIG. Pipe end 2
There is an advantage that a situation in which the outer surface 202 of the tube end 200 is rubbed against the retaining ring 5 and scratched when the 00 is inserted is prevented.

[Effect of device]

According to the present invention, the outer diameter of the outer surface of the pipe end is based on the inner diameter of the elastic seal member even if the outer diameter and wall thickness of the end of the plastic pipe vary widely within the tolerance range. Since the pipe end is set with a stiffener and there is no clearance, the insertion resistance of the pipe end to the joint body is small and workability is good, and moreover, the size within the tolerance range above. Regardless of variations, the compression rate of the elastic seal member is stable, and reliable sealing performance with appropriate surface pressure is maintained for a long period of time. This effect is more prominently exerted by removing the scratched portion by cutting the outer surface of the pipe end and preventing deterioration of the sealing performance of the seal member due to the press fit of the stiffener.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing a connection structure between an insertion joint and a pipe end according to an embodiment of the present invention, FIG. 2 is an explanatory view of a tool used for cutting an outer surface of the pipe end, FIGS. 3 and 4 Is an enlarged partial sectional view of the pipe end whose outer surface is cut, FIG. 5 is a partial sectional view showing a connection structure between a mechanical joint and the pipe end, and FIG. 6 is a connection structure between a conventional insertion joint and the pipe end. Partial sectional views shown, and FIGS. 7 and 8 are partial enlarged sectional views showing the state of the tube end with the stiffener inserted. A ... Plug-in joint, 1 ... Joint body, 4 ... Elastic seal member, 5 ... Stop ring, 200 ... Pipe end, 201 ...
… Stiffener, 202 …… Outer surface of tube end, d ₂ …… Diameter of outer surface of tube end.

Claims (1)

[Scope of utility model registration request] 1. A tubular stiffener is press-fitted into an end portion of a plastic pipe inserted into a plug-in joint in which an elastic seal member and a retaining ring are held in a tubular joint body. The outer surface of the end portion is cut concentrically with the stiffener in a state where the stiffener is press-fitted, and is a smooth surface having a diameter dimension set based on the inner diameter dimension of the elastic seal member in the non-compressed state, Connection between the insertion joint and the pipe end, wherein the elastic seal member is pressed by the outer surface of the end of the plastic pipe and the joint body, and the plastic pipe is retained by the retaining ring. Construction.