JPH11148582A - Plastic pipe fitting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anti-seismic pipe fitting made of plastics with which expansion/contraction and checking the separation can both be obtained compatibly. SOLUTION: The body 2 of pipe fitting into which two plastic pipes 1 are inserted, is configured so that a diametric enlarged part 23 of a socket inner surface is formed between a pipe end ridge 21 and an engaging ridge 22, that engagement with the outside surface 12 is generated at the time of normal water feeding therein so as to establish fixation of the positions of plastic pipes, and that a lock ring 3 is mounted slidably within a ring-shaped space S in the enlarged part 23 along with the pipes in case of emergency, for example in the event of an earthquake. According to this configuration, the lock ring is movable within the ring-shaped space freely while it bites into the outside surface of pipes, so that a margin for expansion and contraction to absorb an external force is assured. After the inter-pipe distance has expanded or contracted exceeding the specified limits, the side face of the lock ring 3 runs against the side face of the pipe end ridge 21 or engaging ridge 22, and a sufficient force for checking the separation will act.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fitting for a plastic pipe used for transporting a fluid such as water supply, gas, and sewage.

[0002]

2. Description of the Related Art In recent years, plastic pipes have been used for water supply, sewage, gas, and other pipes. Compared with conventional cast iron pipes and steel pipes, they have excellent corrosion resistance and can eliminate the need for anticorrosion coating applied to the inner and outer surfaces and are lightweight. Good workability, flexibility, earthquake resistance,
It is evaluated to be advantageous also as a vibration-resistant pipeline. However, it is pointed out that physical properties such as strength, pressure resistance, elongation, etc. are still inferior to steel and other metal materials. There are many cases where it is recognized that the advantage of the buried small-diameter pipe is better than the advantage.

[0003] Naturally, pipe joints are indispensable for the formation of pipelines, from the viewpoint of how efficiently construction can be carried out, and from the viewpoint of how to respond to changes in the ground and impacts after being buried in the ground. , The structure of the pipe joint is compared and evaluated.

FIG. 8 illustrates one of the prior arts.
Both ends of the joint body 102, which is commonly fitted to both ends of the pipe, are raised with tapered surfaces, and a bolt and nut 108 are pressed so as to clamp the rubber ring 103 and the lock ring 107 between the pressing ring 104 having the reverse tapered surface. It is a structure to be fastened with. In this case, the inner core 109 is attached to the inner peripheral surface of the plastic tube 1.
Which is a well-known technique generally employed to reinforce the pressure resistance of plastic tubes. The lock ring 107 is provided with a tooth profile on the inner peripheral surface by dividing it and tightening the press ring 104. The lock ring 107 is pressed by the tapered surfaces to reduce the diameter, and bites into the outer peripheral surface of the plastic pipe to be fixed. As a result, the action of preventing detachment of the plastic pipe is exhibited, and the plastic pipe is completely fixed to the pipe joint,
Although the tube cannot be expanded or contracted, even if a pulling force is applied, the tube is prevented from being detached until the tube breaks. This is why this type of pipe joint is called a detachable mechanical joint.

A pipe joint for an FRP pipe according to Japanese Utility Model Laid-Open Publication No. 63-115986 has a plurality of recesses formed at specific positions on the outer circumference of two pipes to be joined, and is provided commonly for both pipes. This is a prior art in which an insertion hole for inserting a screw bolt into a position corresponding to the concave portion of the joint is drilled, and it is impossible to separate the tubes, but it is difficult to expand and contract the distance between the tubes. 8, the actual joint work such as matching the concave portion and the insertion hole is lost complicatedly, and there may be more problems than the prior art of FIG.

FIG. 9 shows another prior art in which a plastic pipe 201 is opposed on the same axis, a common joint body 202 is externally fitted on the outer peripheral surfaces of both pipe ends, and a tapered surface of the joint body end face is formed. A rubber ring 203 is interposed between the pressing ring 204 and the reverse tapered surface, and the pressing rings 204 are fastened with bolts and nuts 208 to clamp the rubber ring 203. The rubber ring 203 is pinched and exerts a surface pressure necessary for stopping water. In this case, the plastic material is reinforced by applying the inner core 209 in the same manner as in the previous example. However, in view of the function after the joining, the pulling force or the pulling force within the range between the tapered surfaces of the joint body set at the beginning of the joining is given. If an external force of the pressing force acts, the fixing force against this is only the surface pressure of the rubber ring, that is, the frictional force between the outer peripheral surface of the plastic tube and the inner peripheral surface of the rubber ring. Although the distance between the pipe ends can be expanded or contracted, the function of preventing detachment is not provided, and this is the reason why this method is called a telescopic mechanical joint.

In the pipe joint according to Japanese Utility Model Application Laid-Open No. 5-71580, instead of providing a recess in the pipe and locking it with a screw bolt, the tip of the screw bolt that has penetrated the pipe joint is simply the outer peripheral surface of the pipe. The purpose of this is to try to fix the pipe by the frictional force by pressing it.If an external force is applied in the direction of pulling out the pipe, it is possible to extend the distance between the pipes to some extent, but the mechanism to prevent detachment is It can be said that it does not have it and belongs to the same series as the prior art of FIG.

FIG. 10 shows still another prior art, Japanese Utility Model Publication No. 5-009582, in which a plastic tube 301 is provided.
The outer shell 302 fitted to the end of the outer surface has a step and a tapered surface,
An inner screw cylinder 307, an elastic packing ring 303, and a swollen rubber ring 304 are mounted between the inner peripheral surface and the outer peripheral surface of the pipe, that is, in the socket of the pipe joint. Inner screw cylinder 307
A thread is engraved on the inner peripheral surface and meshes with the outer peripheral surface of the plastic pipe, and the outer peripheral surface is fitted with a one-piece annular body composed of a tapered surface having the same gradient as the outer shell 302 so as to expand and contract freely. I have. The inner threaded cylinder 307 is expanded when the plastic tube is inserted, but the elasticity causes the inner thread to bite into the outer peripheral surface of the tube. If a water pressure or a pulling force from the outside acts, a tightening force acts along the tapered surface of the outer shell 302, and the detachment preventing function is realized. The elastic packing ring 303 is sandwiched between the outer shell 302 and the plastic tube 301 by the insertion of the plastic tube and is compressed, so that the surface pressure required for stopping water can be maintained. In addition, the swelling rubber ring 304
Reacts with water leaking from the pipe joints and water intruding from the outside to expand and act to prevent the flow of such water.

[0009]

As represented by the three prior arts cited in the drawings, it is considered that there is no problem in terms of the water stopping performance. However, it cannot be said that there is no possibility that a problem occurs when a pulling force or a compressive force is applied, and this point is a problem that cannot be completely determined in forming a buried pipeline. That is, not only the water pressure but also the external force such as the drawing force and the compressive force acts on not only the plastic pipe but also all the pipelines. In particular, when an earthquake occurs, a very large force with an impact acts. Generally, a plastic pipe has a larger coefficient of linear expansion than a metal pipe, and therefore has a large expansion and contraction due to a temperature change of the pipe. Further, since the modulus of elasticity is small, when water pressure acts, it tends to shrink in the pipe axis direction due to the Poisson's ratio. These act on the pipe joint as a pulling-out force or a compressive force, but it is difficult to deny that each of the conventional techniques has a problem from that viewpoint.

[0010] In the prior art 1 shown in Fig. 8, the detachment preventing force is sufficiently provided, but the expansion and contraction function is lacking. I cannot dispel concerns. Further, since the joint portion does not expand and contract, the diameter of the pipe is reduced by the expansion of the pipe body, and as a result, the flow rate in the pipe may be reduced. If a compressive force is applied, the plastic pipe may bend without absorbing the displacement, and the flow rate in the pipe may be reduced.

The prior art 2 shown in FIG. 9 has a telescopic function but does not have a detachment preventing function. Therefore, when the pulling force is applied and the displacement exceeds a certain level, the detachment is easily performed. If you want to make sure that it does not come off, it is necessary to take the swallowing allowance of the fittings deep enough,
The joint body must be very long, which is a very economically disadvantageous mode.

In the prior art 3 shown in FIG. 10, if a pull-out force acts, the inner threaded cylindrical body further penetrates the outer peripheral surface of the pipe, and the force for preventing the detachment from coming off is further increased. Also, while the inner screw cylinder bites in, it can absorb a small amount of displacement, but since there is no shrinkage allowance in the compression direction, the plastic pipe bends without absorbing the displacement and reduces the flow rate in the pipe. There is no denying that they may cause it.

[0013] As described above, the lack of one of the two important functions of all-purpose utility, particularly, prevention of disengagement and expansion and contraction in any of the prior arts, is a buried pipeline in Japan, which is a country where earthquakes frequently occur. Everyone acknowledges that this is a major concern, and also deems it to be inadequate in terms of resistance to transient eccentric loads due to vehicle traffic and responding to changes such as slow ground subsidence. Not get.
In order to solve the above problems, the present invention has both expansion and contraction functions and detachment prevention functions, responds well to sudden vibrations, vibrations and shocks such as earthquakes, absorbs displacement and absorbs water displacement itself The purpose of the present invention is to provide a pipe fitting for a plastic pipe that reliably guarantees.

[0014]

According to the present invention, there is provided a pipe joint for plastic pipes, in which a pipe main body 2 in which pipe axes 11 are aligned and two pipe ends 11 of two plastic pipes 1 opposed to each other are inserted in common. Between a pipe end projecting symmetrically from the pipe end toward the pipe shaft side and a locking ridge 22 projecting from the pipe end ridge to the pipe shaft side with a shortest distance L1 therebetween. A large-diameter portion 23 on the inner surface of the receiving port is formed in the large-diameter portion 23, meshes with the outer peripheral surface 12 of the plastic tube 1 during normal water flow, and expands together with the plastic tube 1 in an emergency such as an earthquake. The above problem was solved by mounting the lock ring 3 so as to be slidable in the annular space S of the portion 23.

More specifically, the fitting body 2 has a fitting groove 24 recessed substantially at the center of the enlarged diameter portion 23 on the inner surface of the receiving port.
A rubber ring groove 25 is recessed between the locking ridge 22 and the central step 26 of the joint, and the fitting groove 24 is expanded by itself and the spacer ring 4 is divided by 10%. An excellent form is that the lock ring 3 in which a simple tooth form 31 is engraved on the inner surface is overlapped and fitted, and the rubber ring 5 for stopping water is fitted in the rubber ring groove 25.

Further, in the above embodiment, when the cross-sectional length of the lock ring 3 is L2, the extension formed by the side surface of the lock ring 3 and the side surface of the pipe end ridge 21, and the side surface opposite to the lock ring 3 And the amount of shrinkage formed on the side surface of the locking ridge 22 is Q = (L1−L2) / 2, and the distance P between the pipe end 11 of the plastic pipe 1 and the step 26 at the center of the joint body 2 is equal to the distance. Q is slightly longer than Q, more specifically, the mounting of the lock ring 3 is from the groove bottom of the fitting groove 24 recessed in the inner surface of the socket of the joint body 2 to the bulged outer peripheral surface of the joint body. Multiple tap holes 2 penetrating
9 is a set which is inserted into the tap hole 29 and adjusts and presses the lock ring 3 so as to have a restraining force which is superior to the water pressure in the pipe at normal time and inferior to external force in an emergency such as an earthquake. Screwing the bolt 6 leads to an excellent operation.

As another aspect, when the lock ring 3 is fitted into the fitting groove 24, the outer circumferential surface 3 of the lock ring 3
2 is fitted into the groove with a slight step R from the inner surface of the enlarged diameter portion 23, or the enlarged diameter portion on the inner surface of the receiving port of the joint body is enlarged at both ends of the fitting groove 24, In some cases, it is also desirable to form each of the ridges 21 and the locking ridges 22 with the two-gradient inclined diameter-enlarging portion 23A whose diameter is reduced toward the locking ridge 22.

FIG. 4 is a partial longitudinal front view for explaining the basic function of the pipe joint of the present invention, and the lock ring 3 is cut into the outer peripheral surface of the plastic pipe by the above-mentioned structure. Diameter enlarged portion 23 and outer peripheral surface 12 of plastic pipe
And can freely move in the annular space S formed between them, so that an expansion and contraction margin for absorbing external force is expected. Then, after extending beyond a certain amount, as shown in FIG. 4 (A), one side surface of the lock ring 3 collides with the side surface of the pipe end ridge 21 to exert a function of a stopper for preventing further movement. , A sufficient detachment prevention force works. Conversely, when it contracts, the other side surface of the lock ring 3 collides with the side surface of the locking ridge 22 as shown in FIG. Moreover, since the shrinkage allowance Q is set to be smaller than the distance P between the pipe end 11 and the central step 26 at the beginning of the joining, one of the pipe ends 11 moves and hits the central step 26 to be damaged. Such an accident cannot occur. The extension allowance can be freely set by appropriately changing the distance between the pipe end ridge and the locking ridge.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1A is an overall view showing an embodiment of the present invention, and FIG. 1B is an enlarged view of a main part thereof. Has been completed. The joint main body 2 is made as a symmetrical, substantially equal-sized integral body as shown in FIG. 1A, and two plastic pipes 1 opposed to each other are fitted together in common, and a pipe end ridge 2 at the pipe end is provided.
1, an enlarged diameter portion 23 whose inner surface is enlarged in diameter, a fitting groove 24 recessed in the middle of the enlarged diameter portion 23, a locking ridge 22, a locking ridge 22.
The groove 25 for the rubber ring adjacent to the groove, the inclined surface 27 inclined in the joining direction and reaching the central step 26 constitutes a receiving hole on the inner surface of the joint body, and the other is symmetrical from the central step 26 by the reduced diameter portion 28. To form an integral joint body 2.

It goes without saying that the rubber ring 5 is fitted into the rubber ring groove 25 to prevent water leakage from the pipe joint, but as shown in FIG. Since it is arranged at a position closer to the water flow area than the annular space S of the enlarged diameter portion 23 that occurs, it is not only necessary during normal water flow, but also in the event of an emergency such as an earthquake, and the relative positions of the pipes in the joint main body. Even when a large distance is expanded or contracted, the water sealing function always operates to cut off the communication between the annular space S where the movement occurs and the water passage portion in the pipe.

A spacer ring 4 is inserted into a fitting groove 24 that is recessed at the center in the tube axis direction of the enlarged diameter portion 23 on the inner peripheral surface of the socket of the joint body.
And the lock ring 3 are fitted inside and outside. FIG. 2 is a partial sectional view (A) and a side view (B) of the spacer ring 4, and FIG. 3 is a partial sectional view (A) and a side view (B) of the lock ring 3. Both are 41% and 3%, which can be spread freely.
It is manufactured with 3 and receives a suitable external force to reduce its diameter.
The diameter expands when released from external force. In joining the plastic pipes, the split 41 of the spacer ring 4 is compressed and shrunk by the external force, slips through the pipe end ridge 21 smaller than its own diameter, and reaches the fitting groove 24 to form the groove. When the external force is released inside, the diameter expands and adheres to the groove bottom. The same applies to the lock ring 3 which is fitted later to the inner peripheral surface side of the spacer ring 4 in the fitting groove 24, and the two members overlap and are urged toward the outer peripheral surface in a tight manner. Sticking.

The lock ring 3 has a sharp tooth profile 3 on its inner surface.
As shown in FIGS. 3 (A) and 3 (B), 1 is engraved, and is composed of a ring of 33, and is made to expand freely. The diameter can be freely reduced by removing the force, but the diameter is expanded again by the elasticity when the force is removed. As can be understood from FIG. 1B, the inner core 7 has an outer diameter substantially equal to the inner diameter of the plastic pipe to be joined, and has a pipe end 11 at one end.
The other end is tapered and the other end is tapered to facilitate insertion into a plastic tube. Further, it is desirable that the length is set so as to be internally fitted from the pipe end 11 to the mounting portion of the lock ring 3 for reinforcement.

The material of each member is not particularly limited as long as it has strength, rigidity and corrosion resistance other than the rubber ring. For example, as a metal material, an anticorrosion-coated cast iron, a steel material, a copper alloy such as a gunmetal, a stainless steel, or the like is suitable. As the plastic material, an engineering plastic such as polyamide or polyacetal is used. It is necessary to pay particular attention to the elasticity and hardness of the lock ring, and it is preferable to select the lock ring from a copper alloy or stainless steel. It is sufficient that the rubber ring is appropriately selected from synthetic rubber.

The joining procedure of the pipe joint according to the present invention will be described with reference to FIG. (1) Steps up to FIG. 5 (A) (a) Each joint member is attached to the joint body 2 in advance as follows. The rubber ring 5 is mounted in the rubber ring groove 25. The spacer ring 4 is reduced in diameter and inserted from the end of the socket, and fitted into the fitting groove 24 of the enlarged diameter portion 23 on the inner surface of the socket. After mating,
The spacer ring 4 expands in diameter due to its elasticity, and
Attach to the groove bottom of 4. Similarly, the diameter of the lock ring 3 is reduced, and the lock ring 3 is inserted from the pipe end of the socket by digging through the ridge and fitted into the fitting groove 24 of the enlarged-diameter portion 23 on the inner surface of the socket. After fitting, the lock ring 3 expands in diameter due to its elasticity and sticks to the inner surface of the spacer ring 4. The set bolt 6 is screwed into the tap hole 29,
Do not tighten at this time. (B) The end 13 of the plastic tube 1 is chamfered so that it can be easily inserted. The inner core 7 is inserted into the inner surface, and the outer surface of the tube is provided with a marking M indicating an appropriate insertion depth. (2) Steps up to FIG. 5B The pipe is inserted into the joint body 2 using a jack or the like until the position of the marking M on the pipe outer surface reaches the pipe end ridge 21 of the receiving port. (3) Steps up to FIG. 5C When the set bolt 6 is tightened, the diameter of the spacer ring 4 and the lock ring 3 is reduced, and the tooth shape 31 of the lock ring 3 is formed.
Bites into the outer peripheral surface 12 of the plastic tube 1 to complete the joining. Since the lock ring 3 bites into the plastic pipe 1 for the first time by tightening the set bolt 6 in this manner, the lock ring does not contact the outer peripheral surface of the plastic pipe at the time of joining, so that the insertion resistance of the plastic pipe is small. Also, the outer peripheral surface of the pipe is not scratched by the abrasion of the lock ring.

FIG. 6 shows another embodiment of the present invention, in which the outer peripheral surface 32 of the lock ring 3 is fitted into the fitting groove with a slight step R from the enlarged diameter portion 23 of the inner surface of the socket at the time of joining. As described above, the diameter on the inner peripheral side of the spacer ring is large. This configuration can be easily obtained by shortening the length of the set bolt and slightly weakening the urging force for pressing the outer peripheral surface of the spacer ring 4. By fitting the lock ring 3 into the groove by the step R, the force for fixing the positional relationship between the pipes in the joint body against the water pressure test at the time of joining or the thrust force at the time of normal water flow is enhanced. At the same time, when a large withdrawal force or compressive force acts in an emergency such as an earthquake, the lock ring 3 comes off the step R and starts sliding while engaging with the plastic pipe in the enlarged diameter portion on the inner surface of the joint body receiving port. Specifically, it stops by hitting the side face of the locking ridge or the pipe end ridge, and the locking state against external force remains.

FIG. 7 is a longitudinal sectional front view showing still another embodiment of the present invention. As shown in FIGS. 1 and 6, the enlarged diameter portion on the inner surface of the joint main body receiving port is straight, that is, parallel to the pipe axis. By doing so, the engagement force between the lock ring 3 and the outer peripheral surface of the pipe is maintained constant, but the contact pressure between the outer peripheral surface of the lock ring and the enlarged diameter portion of the inner surface of the receiving port is also constant. Therefore, when the pull-out force or the compressive force acts on the joint body 2 to move the plastic pipe, the resistance force during the movement becomes almost constant.
In this state, if an impactful pulling force or compressive force is applied, the plastic pipe may move at a stretch and damage the pipe joint.

FIG. 7 shows an embodiment for canceling such a concern. The diameter of the enlarged diameter portion 23A is set such that the diameter of the enlarged diameter portion near the center is maximized and the diameter is reduced toward both sides.
Formed. In this case, the slope is formed by a straight conical surface, but it may be formed by a curved surface that is reduced in diameter while being curved.
By adopting such a configuration, the contact pressure between the outer peripheral surface 32 of the lock ring 3 and the inclined large-diameter portion 23A surely increases as the plastic pipe moves, so that an impulsive pulling force or compressive force acts. Even when the resistance of the plastic tube to move increases with the movement,
Since the external force is rapidly attenuated, a specific effect is induced that makes it difficult for the impact to directly propagate to the pipe joint with the strong external force.

[0028]

As described above, according to the present invention, since the lock ring is engaged with the outer peripheral surface of the plastic pipe and can be moved integrally within the pressing wheel, transient uneven loads such as earthquakes and traffic of vehicles can be achieved. Even if external force in the pulling direction or pushing direction generated by slow ground subsidence etc. hits directly, the relative spacing between plastic pipes expands and contracts,
Because the limit of the movement range specified by the side of the pipe end ridge and the locking ridge also serves as a stopper, it also functions as a stopper, so it forms an ideal pipeline that has the two major requirements required for seismic joints. Effect appears.

Further, in the pipe joint according to the present invention, since the detachment preventing mechanism and the water stopping mechanism are completely formed separately, it cannot be overlooked that the following secondary effects are included. one of. (1) Since the lock ring and the rubber ring do not directly contact each other, there is no need for a member such as a backup ring for protecting the rubber ring. (2) When a metal material with anti-corrosion coating is used for the pipe joint, the lock ring does not exist in the water passage area, so the joint rapidly expands and contracts. Despite the process of peeling and corrosion of anticorrosive paint, there is an advantage that red water does not mix with tap water and is distributed to the final demand destination.Therefore, a reliable pipeline is provided to support a stable lifeline. There is a factor effect.

When the pipe is buried underground, it is necessary to apply a water pressure by passing water after joining the plastic pipes and to conduct a water pressure test to check for leakage from the joint. Performing this test prior to backfilling with prior art elastic joints may cause the conduit to bend and deviate from the desired shape, as water pressure will tend to move the distance between the tubes within the joint. Sex cannot be denied. That is,
It is difficult to conduct a water pressure test after pipe formation after the soil and sand are backfilled and the position of the plastic pipe is fixed, and if a leak is found as a result of the test, the pipe must be dug up once. Since the repair must be performed afterwards, the reliability of the water pressure test is low and the repair is extremely complicated, so it must be said that this was a large bottleneck in pipe laying. In this case, there is a sufficient binding force against normal water pressure, and there is a great constructional effect that no problem occurs even if the water pressure test is performed without backfilling.

[Brief description of the drawings]

FIG. 1A is an overall longitudinal sectional front view showing an embodiment of the present invention, and FIG.

FIG. 2 is a partially longitudinal front view (A) and a side view (B) of the spacer ring of the same embodiment.

FIG. 3 is a partially longitudinal front view (A) and a side view (B) of the lock ring of the same embodiment.

FIG. 4 is a partially longitudinal front view showing a state in which the joint portion of the same embodiment is extended to the maximum (A) and a state in which the joint is shortened to the maximum (B).

5 (A), 5 (B) and 5 (C) show the construction process of the present invention in a partially longitudinal front view.

FIG. 6 is a partially longitudinal front view showing another embodiment of the present invention.

FIG. 7 is a partially longitudinal front view showing still another embodiment of the present invention.

FIG. 8 is a vertical sectional front view showing a conventional technique.

FIG. 9 is a longitudinal sectional front view showing another conventional technique.

FIG. 10 is a longitudinal sectional front view showing still another conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plastic pipe 2 Fitting main body 3 Lock ring 4 Spacer ring 5 Rubber ring 6 Set bolt 7 Inner core 11 Pipe end 12 Pipe outer peripheral surface 21 Pipe end protrusion 22 Locking protrusion 23 Large diameter portion 23A Increasing diameter large diameter portion 24 Fitting Groove 25 Groove for rubber ring 26 Center step 29 Tap hole 31 Tooth profile 32 Lock ring outer peripheral surface 33 Split P Shortest distance between pipe end at initial joint and center step of joint Q Extension and shrinkage allowance L1 Shortest distance between locking ridges L2 Sectional length of lock ring M Marking S Annular space

Claims (6)

[Claims] 1. In a pipe joint for joining plastic pipes, a joint main body 2 in which pipe ends 11 of two opposite plastic pipes 1 are inserted in common with pipe axes aligned is opened symmetrically in the pipe axis direction. End 21 projecting from the end of the pipe to the pipe axis side
The enlarged diameter portion 23 of the inner surface of the receiving port is provided between the pipe end protrusion 21 and a locking protrusion 22 projecting toward the pipe shaft at a shortest distance L1 from the pipe end protrusion.
Is formed and meshes with the outer peripheral surface 12 of the plastic tube 1 during normal water flow in the enlarged diameter portion 23 to fix the position of the plastic tube. In an emergency such as an earthquake, the annular shape of the enlarged diameter portion 23 together with the plastic tube 1 is formed. A plastic pipe joint, wherein a lock ring 3 is mounted so as to be slidable in a space S. 2. The joint main body 2 according to claim 1, wherein a fitting groove 24 is formed substantially at the center of the enlarged diameter portion 23 on the inner surface of the receiving port, and between the locking ridge 22 and a central step 26 of the joint. A groove 25 for a rubber ring is formed in the groove, and a spacer ring 4 is spread on the fitting groove 24 arbitrarily, and a lock ring 3 engraved with a sharp tooth shape 31 on the inner surface is formed on the spacer. A plastic pipe joint characterized in that a rubber ring 5 for stopping water is fitted into a groove 25 for a rubber ring while being fitted. 3. The lock ring 3 according to claim 1, wherein, when the length of the cross section of the lock ring 3 is L2, an allowance formed by the side surface of the lock ring 3 and the side surface of the pipe end ridge 21 and the lock ring 3 The contraction allowance formed by the opposite side surface and the side surface of the locking ridge 22 is Q = (L1−L2) / 2, and the distance between the pipe end 11 of the plastic pipe 1 and the central step 26 of the joint body 2 A plastic pipe joint, wherein P is slightly longer than the distance Q. 4. The joint ring according to claim 1, wherein the mounting of the lock ring 3 extends from a groove bottom of a fitting groove 24 recessed in an inner surface of a socket of the joint body 2 to a bulged outer peripheral surface of the joint body. A plurality of tap holes 29 are formed, and the lock ring 3 is inserted through the tap holes 29 so as to have a restraining force which is superior to the water pressure in the pipe in a normal state and inferior to an external force in an emergency such as an earthquake.
A plastic pipe joint characterized by screwing a set bolt 6 that adjusts and presses. 5. The outer peripheral surface 32 of the lock ring according to claim 4, wherein the lock ring 3 is fitted into the fitting groove 24.
Is fitted into the groove with a slight step R from the inner surface of the enlarged diameter portion 23. 6. The joint of claim 1, wherein the enlarged diameter portion of the inner surface of the socket of the joint body has the largest diameter at both ends of the fitting groove 24, and extends to the pipe end ridge 21 and the locking ridge 22. A plastic pipe joint characterized in that it is formed by a two-gradient diagonally enlarged portion 23A whose diameter decreases as it goes.