JP2011220443A - Pipe joint for multilayer pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pipe joint for a multilayer pipe, superior in workability, by reliably exhibiting the slip-out preventive function of a pipe, while absorbing thermal expansion-contraction displacement of the pipe.SOLUTION: A first connecting part 2 is pressed by a retainer 60 by inserting a protective ring 40 and seal packing 50 into a first socket 21. An inner peripheral tapered surface 31 is formed on an inner peripheral surface of a first press-ring 30 for pressing the retainer 60, and a lock ring 70 forming a plurality of teeth 71 biting in an outer peripheral surface of the pipe, is installed thereto. A height of the teeth 71 is less than a thickness of an outer peripheral resin layer 97 of the multilayer pipe 90. The lock ring 70 is not arranged in a second connecting part 3, and the multilayer pipe 90 can move in the axial direction.

Description

  The present invention relates to a pipe joint for multilayer pipes for connecting multilayer pipes that are exposed and laid on the ground.

  In railroads in cold regions, in order to eliminate snow accumulation on the track, a snow-sprinking system such as a sprinkler water spray system and a snow-dissipating panel unit type that uses a heat sink with water as a heat medium to melt the snow on the heat sink Is adopted. Various piping materials for supplying a heat medium to the snow-melting system have been proposed.

  For example, Patent Literature 1 discloses a branch joint having a composite resin pipe provided with a resin layer on the inner and outer diameter sides of a tubular metal plate provided with a plurality of opening holes, and a mechanical connection portion for connecting the composite resin pipe. Is disclosed. The mechanical connection part consists of a packing that is mounted between the pipe and the connection part, and a pressing member that presses the packing, and absorbs expansion and contraction while maintaining the fastening force even if the pipe expands and contracts due to changes in temperature. It is supposed to correspond to. Since the composite resin tube is provided with a tubular metal plate, the composite resin tube can be made much lighter than a steel tube, and has a substantially equivalent linear expansion coefficient. Furthermore, since it is excellent in heat retention compared with a steel pipe, it is suitable as a pipe material for supplying a heat medium to the snow-melting system. However, since this mechanical connection portion does not have a function of preventing the pipe from coming off, there is a possibility that the pipe may come out of the connection portion after repeated thermal expansion and contraction for many years.

On the other hand, various proposals have been made as a mechanism for preventing the mechanical connection portion from coming off.
For example, in Patent Documents 2 to 4, a cylindrical stiffener that supports the inner surface of the resin tube and a lock ring that has teeth on the inner surface that bite into the outer surface of the end of the resin tube are mounted. Describes a pipe joint for connecting a resin pipe equipped with a color ring having an inner surface for reducing the diameter of the lock ring. The displacement of the pipe can be absorbed inside the joint.

  Further, Patent Documents 5 to 7 are pipe joints for connecting synthetic resin pipes, which are threadedly engaged with a joint body and formed with an inner circumferential taper surface formed with an inner circumferential tapered surface that expands on the joint body side, and an inner circumferential taper. A pipe joint having an outer peripheral tapered surface facing the surface and a biting ring formed with a plurality of inner peripheral teeth that bite into the pipe is described. When a pulling force is applied to the pipe, the biting ring is pressed against the inner peripheral tapered surface of the press wheel to reduce the diameter, and an effect of preventing the pipe from coming off is obtained.

JP 2007-146992 A Japanese Patent Laid-Open No. 10-281362 JP 2000-028056 A JP 2001-108167 A Japanese Utility Model Publication No. 63-112689 Japanese Utility Model Publication No. 02-071195 Japanese Utility Model Publication No. 06-077862

However, in Patent Documents 2 to 4, the lock ring is attached to the end of the pipe, and the lock ring is locked inside the pipe joint to prevent the pipe from being removed. There is a problem that a work ring at the construction site is large because a lock ring must be attached to the end of the pipe after inserting a push ring, a rubber ring, a coloring ring and the like in advance.
Moreover, although the thing of patent documents 5-7 acts effectively, the displacement by the heat | fever expansion / contraction of a pipe | tube is not taken into consideration, although the fall prevention function of a pipe | tube acts effectively. Also, when applied to composite resin pipes and resin-lined steel pipes, the inner peripheral teeth of the ring penetrate the resin layer on the outer peripheral surface of the pipe, and moisture such as rainwater enters from the penetration part, corroding the metal plate of the pipe There was a risk of being.
The present invention has been made in order to solve the above-described problems, and provides a pipe joint for multilayer pipes that reliably exhibits a function of preventing the pipe from detaching while absorbing thermal expansion / contraction displacement of the pipe and is excellent in workability. For the purpose.

In order to achieve the above object, a pipe joint for multilayer pipes according to the present invention comprises:
A tubular steel body provided with a plurality of opening holes, an inner peripheral resin layer formed on the inner peripheral surface of the steel body, the inner peripheral resin layer and the opening hole are integrally formed, and the steel A pipe joint for connecting a multilayer pipe made of an outer peripheral resin layer provided on the outer peripheral surface of the body,
A stiffener is inserted at the end of the multilayer tube,
A joint body formed with a first receiving port whose diameter increases toward one end, and a first press ring which is fastened by the joint body and fastening means and has an inner peripheral tapered surface facing the receiving port; A protective ring inserted into the first receiving port, a rubber seal packing, a retainer that is pressed by the end face of the first press ring and presses the seal packing, and an outer periphery that faces the inner peripheral tapered surface of the first press ring A first connecting portion having a taper surface and a lock ring formed with a plurality of teeth that bite into the outer peripheral surface of the multilayer pipe, and the height of the plurality of teeth is less than the thickness of the outer peripheral resin layer; ,
A second receiving port that is at the other end of the joint body and expands toward the other end, a second press ring that is fastened by the joint body and fastening means, and a protection inserted into the second receiving port. It comprises a ring, a rubber seal packing, and a second connecting portion having a retainer that is pressed by the end face of the second press ring and presses the seal packing.

  According to the present invention, the height of the teeth of the lock ring of the first connecting portion is less than the thickness of the outer peripheral resin layer, so the teeth of the lock ring do not bite into the steel body of the multilayer pipe, and the multilayer pipe Since the second connection portion does not have a lock ring, the shrinkage amount can be absorbed inside the pipe joint even if the multilayer pipe is thermally expanded and contracted. .

It is a half sectional view of a pipe joint concerning an embodiment of the invention. It is a lock ring used for a pipe joint concerning an embodiment of the invention. It is the A section enlarged view in FIG. It is a perspective view of a multilayer pipe connected to a pipe joint concerning an embodiment of the invention. It is the schematic diagram which connected and constructed the pipe joint and multilayer pipe which concern on embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 4, the multilayer pipe 90 connected to the pipe joint according to the present invention includes a tubular steel body 91 provided with a plurality of opening holes 93 and an inner surface formed on the inner peripheral surface of the steel body 91. The peripheral resin layer 95, and the inner peripheral resin layer 95 and the outer peripheral resin layer 97 that are integrally formed through the opening hole 93 and provided on the outer peripheral surface of the steel body 91. The inner peripheral resin layer 95 and the outer peripheral resin layer 97 are, for example, high density polyethylene (HDPE).
Since the multilayer pipe 90 has the steel body 91, the linear expansion coefficient is 1.2 × 10 ⁻⁵ / K, which is almost the same as that of the steel pipe. And if the surface temperature of the tube when exposed to direct sunlight in summer is about 60 ° C and the winter minimum temperature in cold regions is about -20 ° C, the temperature difference will be 80 ° C and the coefficient of thermal expansion will be about 0.1%. It is. If the total length of the multi-layer tube is 5 m, the expansion and contraction of 5 mm is repeated due to the difference in temperature between years. This amount of expansion and contraction is a very small value compared to a polyethylene pipe not having a steel body. Moreover, since it has the inner periphery resin layer 95 and the outer periphery resin layer 97, it is excellent in heat retention compared with a steel pipe, and is substantially equivalent to the polyethylene pipe without a steel body. Therefore, it is suitable as a pipe material for supplying a heat medium to a snow-melting system laid along the track.

  As shown in FIG. 1, the pipe joint 1 according to the embodiment of the present invention includes a joint body 20 in which a first receiving port 21 whose diameter is enlarged toward an end portion, a joint body 20, a bolt 81, and a nut 82. The first press ring 30 which is fastened and formed with the inner peripheral tapered surface 31 facing the first receiving port 21, the metal protective ring 40 inserted into the first receiving port 21, the rubber seal packing 50, the first A retainer 60 that presses the seal packing 50 and is pressed by the end surface of the pusher wheel 30, an outer peripheral tapered surface 73 that faces the inner peripheral tapered surface 31 of the first presser wheel 30, and a plurality of teeth 71 that bite into the outer peripheral surface of the multilayer tube 90. A first connection portion 2 having a lock ring 70 formed with a second receiving port 25 at the other end portion of the joint body 20 and having a diameter increasing toward the other end portion; Fastened with bolts 81 and nuts 82 A second press ring 35, a metal protection ring 40 inserted into the second receiving port 25, a rubber seal packing 50, and a retainer 60 that is pressed by the end face of the second press ring 35 and presses the seal packing 50. And two connection portions 3. A cylindrical metal stiffener 85 is inserted in the inner periphery of the end of the multilayer tube 90 to prevent the multilayer tube 90 from being reduced in diameter.

In the joint body 20, a flange portion 28 having a through-hole 27 through which the bolt 81 passes is formed on the outer periphery of the first receiving port 21 and the second receiving port 25, and the first receiving port 21 and the second receiving port 25 are communicated. A flow path 23 is formed. The joint body 20 is made of malleable cast iron and has a rust-proof coating on the surface.
The flow path 23 has such a length that the multi-layer pipes 90 do not collide with each other even after the multi-layer pipe 90 is connected from both sides of the first receiving port 21 and the second receiving port 25. This is a length absorption allowance when the multilayer tube 90 is thermally expanded and contracted.
The first push ring 30 is formed with a flange portion 38 in which a through hole 37 opposite to the through hole 27 of the joint body 20 is formed, and is made of malleable cast iron and has a rust-proof coating on the surface.
The second presser wheel 35 is a ring-shaped member in which a flange portion 38 formed with a through hole 37 opposite to the through hole 27 of the joint body 20 is formed, and an insertion hole 36 through which the multilayer tube 90 is inserted is formed. Since the second connection portion 3 does not have a retaining mechanism, the second pusher wheel 35 may be lower in strength than the first pusher wheel 30, and is made of, for example, a synthetic resin.

The protection ring 40 is a member that prevents the seal packing 50 from moving to the back side of the joint body 20 when the seal packing 50 is pressed by the retainer 60. The protection ring 40 has an insertion hole through which the multilayer tube 90 is inserted and an outer peripheral surface. The outer peripheral taper surface opposite to the taper surface of the receiving ports 21 and 25 is formed. The material should just be harder than the hardness of the seal packing 50, for example, is made from polyacetal (POM).
The seal packing 50 is a ring-shaped rubber packing that seals the inner peripheral surface of the joint body 20 and the outer peripheral surface of the multilayer tube 90 in a water-tight manner. ) Is preferable.
The retainer 60 is a polyacetal (POM) ring-shaped member, and has a small-diameter portion that presses the seal packing 50 and a large-diameter portion that is pressed by the push wheels 30 and 35.

  As shown in FIG. 2, the lock ring 70 is a substantially C-shaped metal ring having a notch 75 at one location, and an outer peripheral tapered surface 73 opposite to the inner peripheral tapered surface 31 is formed on the inner peripheral surface. Teeth 71 that bite into the multilayer tube 90 are formed. The teeth 71 are ridges formed continuously in a sawtooth shape, and the height of the irregularities is provided less than the thickness of the outer peripheral resin layer 97 of the multilayer tube 90. For example, when the thickness of the outer peripheral resin layer 97 is 2 mm, the height of the unevenness of the teeth 71 is 1 mm, which is ½ of the thickness of the outer peripheral resin layer 97, and is continuously provided in ten strips.

3A to 3C show more specific forms of the teeth 71. FIG.
FIG. 3A includes ten teeth 71a having symmetrical acute angles (for example, 40 °) in cross section, and a smooth surface 77 is formed between the teeth 71a. In this case, the height Ha of the teeth 71a is set to be less than the thickness of the outer peripheral resin layer 97 of the multilayer tube 90. The ratio Pa / ta between the length Pa of the smooth surface 77 and the base length ta of the teeth 71a is the shear strength of the resin material constituting the outer peripheral resin layer 97 and the shear strength of the metal material constituting the teeth 71a. What is necessary is just to set by ratio.
According to the form of the tooth 71a, since it has a cross-sectionally symmetric shape, the pulling-in preventing force and the pushing-in preventing force are exhibited almost equally with respect to the displacement of the multilayer tube 90. The drawing means displacement in the direction in which the multilayer pipe 90 is pulled out from the pipe joint 1, and pushing in means the displacement in the direction in which the multilayer pipe 90 is pushed into the pipe joint 1.

FIG. 3 (b) has ten teeth 71b having a sawtooth cross-section with a vertical surface formed on the side where the outer peripheral tapered surface 73 is reduced in diameter, and a smooth surface 77 between the teeth 71b and the teeth 71b. Is formed. In this case, the height Hb of the teeth 71b is set to be less than the thickness of the outer peripheral resin layer 97 of the multilayer tube 90. The ratio Pb / tb between the length Pb of the smooth surface 77 and the base length tb of the teeth 71b is the shear strength of the resin material constituting the outer peripheral resin layer 97 and the shear strength of the metal material constituting the teeth 71b. What is necessary is just to set by ratio.
According to the form of the teeth 71b, when a pulling force is applied to the multilayer tube 90, the lock ring 70 is reduced in diameter along the inner peripheral tapered surface 31, so that a high pulling preventing force is obtained. Further, when a pushing force is applied to the multilayer tube 90, the vertical surface of the teeth 71b becomes a resistance, so that a high pushing prevention force can be obtained.

FIG. 3 (c) has 10 teeth 71c having a sawtooth cross-section with a vertical surface formed on the side where the outer peripheral tapered surface 73 expands, and a smooth surface 77 between the teeth 71c and the teeth 71c. Is formed. In this case, the height Hc of the teeth 71c is set to be less than the thickness of the outer peripheral resin layer 97 of the multilayer tube 90. The ratio Pc / tc between the length Pc of the smooth surface 77 and the base length tc of the teeth 71c is the shear strength of the resin material constituting the outer peripheral resin layer 97 and the shear strength of the metal material constituting the teeth 71c. What is necessary is just to set by ratio.
According to the form of the teeth 71c, when a pulling force is applied to the multilayer tube 90, the lock ring 70 is reduced in diameter along the inner peripheral tapered surface 31, and the vertical surface of the teeth 71c becomes a resistance. Compared with the configuration of 71b, a higher pulling-in preventing force can be obtained.

  Which form of the teeth 71a, teeth 71b, and teeth 71c is adopted can be selected according to the form of displacement applied to the multilayer tube 90, and the slip-off prevention force and the push-in prevention force of the first connection portion 2 are At least the frictional resistance between the seal packing 50 of the second connecting portion 3 and the multilayer tube 90 is exceeded. In addition, since it has the smooth surface 77, it does not bite into the multilayer pipe 90 more than height Ha-Hc of the teeth 71a-71c.

  Returning to FIG. 1, when the insertion allowance for the pipe joint 1 is marked and inserted on the outer peripheral surface of the multilayer pipe 90, and the bolt 81 and the nut 82 are tightened, the retainer 60 is pressed against the push wheels 30 and 35. By pressing the seal packing 50, the seal packing 50 seals the inner peripheral surface of the joint body 20 and the outer peripheral surface of the multilayer tube 90 in a watertight manner. At this time, the inner peripheral tapered surface 31 of the first push ring 30 presses the outer peripheral tapered surface 73 of the lock ring 70, and the teeth 71 bite into the outer peripheral surface of the multilayer tube 90.

As shown in FIG. 5, the plurality of multilayer pipes 90 are connected to the plurality of pipe joints 1 and are laid along the railroad track. At this time, one end side of the multilayer pipe 90 is connected to the first connection part 2 of the pipe joint 1, and the other end side is connected to the second connection part 3 of another pipe joint 1, and the pipe joint 1 is laid with a fixture 100. Fixed to the surface 110. The fixing tool 100 is formed by joining two semicircular arc metal bands 101 and 102 so as to straddle the outer periphery of the pipe joint 1 and fastening them with bolts and nuts 102, and is fixed to the laying surface 110 on one metal band 102. It has a fixed surface 103.
When thermal expansion and contraction due to a change in air temperature is applied to the multilayer pipe 90, the relative position between the pipe joint 1 and the multilayer pipe 90 is not changed by the action of the lock ring 70 in the first connection portion 2. And since the height of the unevenness of the teeth 71 of the lock ring 70 is less than the thickness of the outer peripheral resin layer 97 of the multilayer tube 90, it does not bite to the extent that it penetrates the outer peripheral resin layer 97.

  On the other hand, in the second connection portion 3, the multilayer tube 90 freely expands and contracts along the inner peripheral surface of the seal packing 50. That is, the pipe joint 1 is fixed by the fixture 100, and the first connection portion 2 has a retaining force and a push-in preventing force that are at least a frictional resistance force between the seal packing 50 of the second connection portion 3 and the multilayer tube 90. Therefore, even when the multilayer tube 90 expands and contracts, the relative positions of the laying surface 110, the pipe joint 1 and the multilayer tube 90 change. There is nothing.

1: pipe joint, 2: first connection part, 3: second connection part 20: joint body, 21: first receiving port, 23: flow path, 25: second receiving port, 27: through hole, 28 : Flange part 30: 1st push ring, 31: Inner circumference taper surface, 35: 2nd push ring, 36: Insertion hole, 37: Through-hole, 38: Flange part,
40: protection ring, 50: seal packing, 60: retainer,
70: Lock ring, 71: Teeth, 73: Peripheral tapered surface,
81: bolt, 82: nut, 85: stiffener,
90: multilayer pipe, 91: steel body, 93: opening hole, 95: inner peripheral resin layer, 97: outer peripheral resin layer

Claims (1)

A tubular steel body provided with a plurality of opening holes, an inner peripheral resin layer formed on the inner peripheral surface of the steel body, the inner peripheral resin layer and the opening hole are integrally formed, and the steel A pipe joint for connecting a multilayer pipe made of an outer peripheral resin layer provided on the outer peripheral surface of the body,
A stiffener is inserted at the end of the multilayer tube,
A joint body formed with a first receiving port whose diameter increases toward one end, and a first press ring which is fastened by the joint body and fastening means and has an inner peripheral tapered surface facing the receiving port; A protective ring inserted into the first receiving port, a rubber seal packing, a retainer that is pressed by the end face of the first press ring and presses the seal packing, and an outer periphery that faces the inner peripheral tapered surface of the first press ring A first connecting portion having a taper surface and a lock ring formed with a plurality of teeth that bite into the outer peripheral surface of the multilayer pipe, and the height of the plurality of teeth is less than the thickness of the outer peripheral resin layer; ,
A second receiving port that is at the other end of the joint body and expands toward the other end, a second press ring that is fastened by the joint body and fastening means, and a protection inserted into the second receiving port. A pipe joint for multilayer pipes comprising a ring, a rubber seal packing, and a second connecting portion having a retainer that is pressed by an end face of the second press ring and presses the seal packing.

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