JP4380851B2 - Structure of pipe joint - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to the structure of a pipe joint.
[0002]
[Prior art]
Recently, high-density polyethylene pipes that are lightweight, corrosion-resistant, and cold-resistant are widely used for water supply pipes. For joining high-density polyethylene pipes, pipe insertion holes are inserted into flange pipe joints, and press rings are used. There is used a dresser joint that is externally fitted to a pipe and in which a flange pipe joint and a press ring are fastened by a T-head bolt and a nut.
[0003]
[Problems to be solved by the invention]
However, the high-density polyethylene pipe has a large coefficient of linear expansion, and the outer diameter changes greatly due to changes in temperature. Therefore, if a large bending stress or axial stress is applied due to a change in environmental temperature, it tends to be pulled out from the dresser joint. was there.
[0004]
An object of the present invention is to solve the above-mentioned conventional problems and to provide a structure of a pipe joint portion in which a high-density polyethylene pipe does not fall out from a flange pipe joint even when a large bending stress or axial stress is applied.
[0005]
[Means for Solving the Problems]
The structure of the pipe joint portion of the invention of claim 1 is a flange pipe joint in which a rubber ring having an outer peripheral surface inclined in a substantially conical shape and a small diameter portion tip bulged in a substantially circular cross section is inserted into a receiving port. The insertion port of the high-density polyethylene pipe with the in-core inserted into the tip is inserted, and the lock ring that can be reduced in diameter with an axial cut and the small diameter part of the retainer having a stepped part on the outer periphery are A press ring inserted in this order in a concave part whose diameter is slanted is fitted to the high-density polyethylene pipe, and the large diameter part of the retainer is sandwiched between the rubber ring and the press ring, and the flange fitting And the press ring are fastened by T-head bolts and nuts , and the in-core is provided with a flange at one end thereof, and a groove is provided in the circumferential direction adjacent to the flange, and a hook-like protrusion is provided at the recess. The strip is projected outward from the peripheral wall of the in-core .
[0006]
In the structure of the pipe joint part of the invention of claim 1, the material of the flange pipe joint and the press ring is preferably spheroidal graphite cast iron having a tensile strength of 450 MPa or more, a proof stress of 280 MPa or more, and an elongation of 10% or more. .
[0007]
In the pipe joint structure according to the first aspect of the present invention, the material of the rubber ring is not particularly limited. For example, styrene-butadiene rubber (SBR), ethylene-propylene-diene terpolymer (EPDM), etc. A rubber having excellent heat resistance is preferably used.
[0008]
In the structure of the pipe joint part of the invention of claim 1, the material of the in-core inserted into the insertion port of the high-density polyethylene pipe is particularly limited as long as the tensile strength is 450 MPa or more and the elongation is 10% or more. For example, metal such as cast iron, steel, stainless steel, aluminum, aluminum casting, copper, copper alloy casting, fiber reinforced resin with reinforcing material such as glass fiber, carbon fiber, etc., copper, copper alloy Casting is preferably used.
[0009]
The length of the in-core needs to be larger than the length from the pipe end of the high-density polyethylene pipe to the outer fitting portion of the press ring so that the occurrence of cold flow due to tightening of the lock ring or rubber ring can be suppressed.
[0010]
In the structure of the pipe joint portion of the invention of claim 1 , the lock ring and the retainer are made of a material having a tensile strength of 370 MPa or more, a yield point of 215 MPa or more, a longitudinal elongation of 30% or more, and a lateral elongation. 25% or more of carbon steel for mechanical structure is preferably used.
[0011]
It is preferable that circumferential ridges having a substantially triangular cross section are arranged in parallel on the inner circumference of the lock ring, and one surface of the ridge may be perpendicular to the axial direction. The inclination angle of the protrusion is not particularly limited as long as it is in the range of 30 to 80 °, and is preferably set to 30 to 60 °. The number of ridges is preferably 4-6.
[0012]
In the structure of the pipe joint portion of the invention of claim 1, the shape of the retainer is a cylindrical shape provided with a step portion on the outer periphery, and the outer diameter of the large diameter portion is larger than the inner diameter of the press ring, and the small diameter portion. The outer diameter is smaller than the inner diameter of the press wheel.
[0013]
In the pipe joint structure according to the first aspect of the invention, the paint used for painting the flange joint, press ring, lock ring, and retainer does not contain any harmful components in use and dissolves in water after drying. In addition, an epoxy resin powder coating is preferably used and electrodeposition coating may be performed.
[0014]
In the structure of the pipe joint portion according to the first aspect of the present invention, the material of the T-head bolt and nut is not particularly limited, but spheroidal graphite cast iron or stainless steel is preferably used.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the structure of the pipe joint portion according to the first aspect of the present invention will be described below with reference to the drawings.
1 is a cross-sectional view showing an example of the structure of the pipe joint portion of the invention of claim 1, and FIG. 2 is a cut end face of a rubber ring used in the structure of the pipe joint portion of the invention of claim 1 shown in FIG. 3 is a cut end view of the lock ring, and FIG. 4 is a cut end view of the in- core.
[0016]
In the structure of the pipe joint portion according to the first aspect of the present invention shown in FIG. 1, reference numeral 1 denotes a flange pipe joint provided with receiving ports 11 at both ends. As shown in FIG. 2, a rubber ring 2 having an outer peripheral surface inclined in a substantially conical shape and a tip of a small diameter portion bulged into a substantially circular cross section is inserted into the receiving port 11.
[0017]
Reference numeral 3 denotes a press ring provided with a recessed portion 31 whose inner surface is diagonally reduced in diameter on the one surface. The recessed portion 31 has a lock ring 4 having an axial cut and a diameter that can be reduced. The small-diameter portion 51 of the retainer 5 having a portion is inserted in this order.
[0018]
On the inner peripheral surface of the lock ring 4, as shown in FIG. 3, four circumferentially extending protrusions 41 having a substantially triangular cross section are arranged at equal intervals, and one half of the outer periphery is slanted. It is chamfered.
[0019]
Reference numeral 6 denotes a high-density polyethylene pipe, and an in-core 7 is inserted into the tip. As shown in FIG. 4, the in-core 7 has a flange edge 71 provided around one end thereof, and a hook-shaped protrusion 73 is provided in the in-core 7 in a groove 72 provided in the circumferential direction adjacent to the edge. It protrudes outward from the surrounding wall.
[0020]
[Example 1]
First, a lock ring 4 and a small diameter portion 51 of a retainer 5 having a stepped portion on the outer periphery are inserted into two high density polyethylene pipes 6 having a diameter of 75, 100, 150, and 200 mm into which the in-core 7 is inserted. After the press ring 3 inserted in order was externally fitted, the insertion port was inserted into the receiving port 11 of the flange fitting 1.
[0021]
Next, a T-head bolt 8 is inserted into the through-hole 13 of the flange 12 of the flange fitting 1 and the through-hole 33 of the flange 32 of the press ring 3, and the nut 9 is screwed together. The large-diameter portion 52 of the retainer 5 was sandwiched between them and fastened together, and the high-density polyethylene pipes 6 were joined.
[0022]
Both ends of the high density polyethylene pipe 6 joined to each other were fixed to a tension jig and pulled at a pulling rate of 100 mm / min in an environment of −15 ° C. to perform a pulling test. As a result, none of the high-density polyethylene pipes dropped out from the joint, and the original pipe was broken.
[0023]
[Comparative example]
Two high-density polyethylene pipes with a diameter of 75, 100, 150, and 200 mm into which the in-core 7 is inserted are provided with a plurality of protrusions continuously arranged in the circumferential direction on the inner peripheral surface of the press ring. Bonding was performed using a dresser joint for a vinyl chloride pipe with a mechanism, and a pull-out test was performed in the same manner as in Example 1. As a result, the high-density polyethylene pipe was dropped from the joint.
[0024]
【The invention's effect】
The structure of the pipe joint portion of the invention of claim 1 is configured as described above, and the lock ring is pushed into the inner portion of the recessed portion by the retainer. Therefore, even if a large bending stress or axial stress is applied, the structure is high. The density polyethylene pipe does not fall out of the flange fitting.
Also, the incore is provided with a concave groove in the circumferential direction adjacent to the flange edge provided at one end, and the saddle-like ridge protrudes outward from the peripheral wall of the incore in this concave groove. The in-core can be prevented from coming off when the hook-shaped protrusion bites into the inner surface of the high-density polyethylene pipe.
[0025]
[Brief description of the drawings]
1 is a cross-sectional view showing an example of the structure of a pipe joint portion according to the invention of claim 1;
2 is a cut end view of a rubber ring used in the structure of the pipe joint portion of the invention of FIG. 1 shown in FIG. 1;
FIG. 3 is a cut end view of a lock ring used in the structure of the pipe joint of the invention of claim 1 shown in FIG. 1;
4 is a cut end view of the in-core used in the structure of the pipe joint portion of the invention of FIG. 1 shown in FIG. 1;
[Explanation of symbols]
1 Flange fitting 2 Rubber ring 3 Push ring 4 Lock ring 5 Retainer 6 High-density polyethylene pipe 7 In-core 8 T-head bolt 9 Nut
11 Entrance
12 Flange (of flange fitting)
13 Through hole (of flange fitting)
31 depression
32 Flange (of press ring)
33 Through hole (for pusher wheel)
41 ridges
51 Small diameter part
52 Large diameter part
71
72 groove
73 ridges

Claims (1)

A high-density polyethylene pipe with an in-core inserted into the flange fitting with a rubber ring whose outer peripheral surface is inclined in a substantially conical shape and the tip of the small diameter portion is bulged into a substantially circular cross section. A lock ring that has an axial cut and can be reduced in diameter, and a small diameter portion of a retainer having a stepped portion on the outer periphery, are inserted into a recessed portion whose inner diameter is obliquely reduced. The press ring inserted in sequence is externally fitted to the high-density polyethylene pipe, the large diameter portion of the retainer is sandwiched between the rubber ring and the press ring, and the flange pipe joint and the press ring are fastened by the T-head bolt and nut , The in-core is provided with a flange edge at one end, and a groove is provided in the circumferential direction adjacent to the flange edge, and a hook-shaped protrusion protrudes outward from the peripheral wall of the in-core. A structure of a pipe joint characterized by having

Images