JPH0814458A - Synthetic resin joint for resin flexible pipe and manufacture thereof - Google Patents

Abstract

PURPOSE:To prevent easy generation of relaxation of stress in a tightening part between a nut body and a connection port part, simultaneously eliminate corrosion and rust of the nut body and the connection port part. CONSTITUTION:A connection port part 10, formed of synthetic resin of nylon 66 or the like excellent in mechanical strength and rarely generating relaxation of stress, is connected to a polyethylene-made short pipe 1. A nut body 2 is made of synthetic resin of polyacetal or the like excellent in mechanical strength and rarely generating relaxation of stress.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic resin joint for a flexible resin tube used in piping for handling combustible gas and the like, and a method for producing the same.

[0002]

2. Description of the Related Art Polyethylene resin flexible pipes and polyethylene straight pipes are often used as the above pipes.

When a polyethylene pipe such as a resin flexible pipe or a straight pipe is connected in a flammable gas pipe using such a polyethylene pipe, the end portion of the pipe inserted into the tubular joint is A common method is to expand the ductile metal body that is deployed along its inner surface by expanding it and press the pipe wall at the end of the pipe against the packing or retaining groove provided on the joint side. (First conventional example).

On the other hand, a resin flexible tube made of polyethylene and a polyethylene straight tube may be connected by using a joint for a resin flexible tube disclosed in Japanese Utility Model Publication No. 3-125978. . This joint is shown in FIG.

This joint has a split retaining ring 120 that is set in the connection opening 101 when the nut body 110 is screwed into the cylindrical connection opening 101 provided integrally with the pipe 100. By pushing the nut body 110 backward, the protrusions 121 of the retaining ring 120, which are pre-engaged between the peaks a1 and a1 of the resin flexible tube A inserted in the connection port 101, The end portion A1 of the flexible tube A is pushed and moved forward, and the end portion A1 of the resin flexible tube A can be pushed against the annular convex portion 102 provided in the pipe portion 100 by the pressing action at that time.

According to this joint, when the nut body 110 is completely tightened, the protrusions 121 of the retaining ring 120 and the protrusions 102 of the pipe portion 100 cause the ends 1 to 1 of the end portion A1 of the flexible resin tube A to be 1 to 1. The portion of about three peaks is pressed and the convex portion 102 and the end portion A1 of the resin flexible tube A come into close contact with each other. In addition, the recess 1 is formed on the outer peripheral portion of the convex portion 102 of the pipe 100.
03 is formed and a rubber ring 130 such as an O-ring is housed in the recess 103, and the end portion A1 of the resin flexible tube 1 is pressed against the rubber ring 130 to seal the above-mentioned contact portion. There is also one (second conventional example).

[0007]

However, when the above-mentioned connection method is adopted as the first conventional example, it is difficult to absorb the tolerance of the inner surface working accuracy of the joint and the dimensional accuracy of the synthetic resin pipe. There was an occasion.

In the joint described above as the second conventional example, the nut body 110 is completely tightened, and the pipe portion 1
After the end portion A1 of the resin flexible tube A is pressed against the convex portion 102 of 00 and the rubber ring 130, the retaining ring 1
If the pressing force on the resin flexible tube A by 20 loosens for some reason, the adhesion of the end portion A1 of the resin flexible tube A to the convex portion 102 and the rubber ring 130 will be impaired. In order to prevent such a decrease in adhesion, the pipe portion 100 integrally provided with the connection port portion 101 and the nut body 110 are made of metal, so that a screwing point between the nut body 110 and the connection port portion 101 is screwed. It can be said that it is effective to prevent stress relaxation in the (fastening portion) 140.

However, if the pipe portion 100 and the nut body 110 integrally provided with the connection port portion 101 are made of metal, not only there is a possibility that they will corrode or rust over time, but also the pipe portion 100 As a means for connecting the synthetic resin pipe to the tip end, for example, there is a problem that the method described as the above-mentioned first conventional example has to be adopted.

Therefore, the nut body 110 and the connection port 10
It is conceivable to integrally manufacture 1 and the pipe portion 100 with polyethylene, and by doing so, the problems of corrosion and rusting over time are solved. However, the nut body 110
If the connection port 101 is polyethylene, stress relaxation is likely to occur in the fastening portion 140 between the nut body 110 and the connection port 101 due to the property of polyethylene, and when stress relaxation occurs, the retaining ring 120 causes the resin to flex. The pressing force against the tube A is loosened, and the adhesion of the end portion A1 of the resin flexible tube A to the convex portion 102 and the rubber ring 130 is impaired.

The present invention has been made in view of the above problems and circumstances. That is, the present invention has the basic structure of the joint of the second conventional example described in FIG. 11, the nut body and the connection port are made of a synthetic resin that is free from the risk of corrosion and rusting, and have the connection port. Although the polyethylene pipe can be easily joined to the short pipe (corresponding to the pipe portion 100), the flexible resin is less likely to cause stress relaxation at the fastening portion between the nut body and the connection opening portion. An object is to provide a synthetic resin joint for pipes.

Further, according to the present invention, when the connection port is injection-molded to the previously molded short pipe and the connection is provided, the end of the short pipe to which the connection port is joined is thermally deteriorated and becomes weak. It is an object of the present invention to provide a method of manufacturing a synthetic resin joint for a flexible resin tube that hardly causes a situation.

[0013]

According to a first aspect of the present invention, there is provided a synthetic resin joint for a flexible resin tube having a structure as set forth in claim 1, wherein a proximal end of a short pipe made of polyethylene, to which a synthetic resin pipe body for piping is connected, at a distal end portion thereof. Is connected to a tubular connection port made of synthetic resin that is less likely to cause stress relaxation than the short pipe, and is fitted to the resin flexible pipe inserted into this connection port to the connection port. The nut body to be screwed in is made of synthetic resin that is less likely to cause stress relaxation than the short pipe, and includes a retaining ring that can be reduced in diameter and is set in the connection port portion. An annular overhang is provided inward at the front end of the, and the inner diameter of the overhang is formed by a circular-cylindrical cylindrical body that is larger than the outer diameter of the resin flexible tube. A tapered surface is formed on the outer periphery of the overhanging part, Has a contact portion that allows the diameter of the retaining ring to be reduced while pushing the retaining ring when it is screwed into the connecting port, and the connecting port portion of the retaining ring that is pushed by the nut body. It has a tapered guide surface that slides on the tapered surface to advance the retaining ring radially inward while reducing its diameter. An annular convex portion that abuts on an end portion of the resin flexible tube that is advanced by engaging with the portion,
The protrusion is provided on the inner peripheral portion of the convex portion and is fitted in the end portion of the resin flexible tube to support the end portion from the inside. The synthetic resin joint for a flexible resin tube having the structure described in claim 2 is the same as that described in claim 1, wherein the bulging of a short pipe made of polyethylene having a bulging portion with a large diameter at the base end. The part is that the short pipe and the connection port are joined by being fitted and pressed into the concave groove provided in the cylindrical connection port made of synthetic resin that is less likely to cause stress relaxation than the short pipe. is there. A synthetic resin joint for a flexible resin tube having the structure described in claim 3 has the same type as the short pipe at the base end portion of the short pipe made of synthetic resin to which the synthetic resin pipe body for piping is connected at the tip portion. A cylindrical connection port made of synthetic resin is integrally provided,
The nut body screwed into the connection port portion while being externally fitted to the resin flexible tube inserted into the connection port portion is made of synthetic resin, and the diameter of the nut that can be reduced in diameter is set in the connection port portion. With a retaining ring, the retaining ring is
An annular projecting portion is provided inward at the front end of the cylindrical portion, and the projecting portion is formed by a truncated circular cylinder whose inner diameter is larger than the outer diameter of the resin flexible tube. , A tapered surface is formed on the outer periphery of the protruding portion, and the nut body has a contact portion that pushes the retaining ring backward when screwed into the connection port portion and allows the retaining ring to be reduced in diameter. The connection port includes a tapered guide surface that slides on the tapered surface of the retaining ring that is pushed by the nut body to advance the retaining ring while radially reducing the retaining ring. The short pipe is provided on the inner peripheral portion of the annular convex portion that comes into contact with the end portion of the resin flexible tube that is advanced by engaging with the extended portion of the retaining ring with a reduced diameter. Is fitted into the end of the flexible resin tube and supports that end from the inside. Is that having the projection. The synthetic resin joint for a flexible resin tube having the structure described in claim 4 has a large-diameter engagement portion at a base end portion of a polyethylene short tube to which a synthetic resin pipe body for piping is connected at a distal end portion. A cylindrical connection port made of synthetic resin, which is provided in a bulging shape and is less likely to cause stress relaxation than the short pipe, is fitted outside the engagement part, and is radially inwardly provided in the connection port. The engaging portion of the short pipe is held by a pressing member screwed into the base portion of the connection opening portion and the annular engagement portion that protrudes to the resin flexible tube inserted into the connection opening portion. The nut body screwed into the connection port in the externally fitted state is made of a synthetic resin that is less likely to cause stress relaxation than the short pipe, and the diameter of the retaining ring is set to the connection port and can be reduced in diameter. The retaining ring is provided with an annular protruding portion facing inward at the front end of the cylindrical portion. And an inner peripheral diameter of the overhanging portion is formed by a cylindrical body having a larger diameter than the outer diameter of the resin flexible tube, and a tapered surface is formed on the outer periphery of the overhanging portion. The nut body has a contact portion that allows the diameter of the retaining ring to be reduced while pushing the retaining ring back when it is screwed into the connecting port portion, and the connecting port portion is retained by the nut body to be pushed backward. The short pipe is provided with a tapered guide surface that slides on the tapered surface of the ring and advances while radially reducing the retaining ring radially inward. An annular convex portion that abuts the end portion of the resin flexible tube that meshes with the overhanging portion and is advanced, and an inner peripheral portion of the convex portion that is fitted into the end portion of the resin flexible tube and that end And a protrusion that supports the portion from the inside. A method for manufacturing a synthetic resin joint for a flexible resin tube according to claim 5 is a method for manufacturing a synthetic resin joint for a flexible resin tube according to claim 2, wherein the bulging portion having a large diameter at the base end portion. Set the polyethylene short tube provided with in the molding die, inject the molten synthetic resin into the molding space around the base end of the short tube, and before injection molding the connection port, The ends are coated with a high heat resistant heat insulating material made of a synthetic resin such as a polyamide-based synthetic resin or a synthetic resin reinforced with glass fibers or carbon fibers, and then the connection of the above-mentioned connection port portion through the heat insulating material. This is to form a large-diameter bulging portion at the base end portion of the short tube in the groove.

[0014]

According to the structure described in claim 1, in the state where the nut body is screwed into the connection port and the retaining ring is set in the connecting port, the retaining ring has an inner peripheral diameter of the overhang portion. Is enlarged to be larger than the outer diameter of the corrugated resin flexible tube. In this state, after inserting the resin flexible tube into the nut body, retaining ring and connection port, and then screwing in the nut body, the retaining ring pushed by the nut body causes the retaining ring to move between the tapered surface and the connection port. By the action of the guide surface, the diameter of the resin flexible tube advances while the diameter of the resin flexible tube advances, and the projecting portions engage with each other between the crests of the resin flexible tube to press the end of the resin flexible tube against the convex portion of the short tube. Further, the protrusions provided on the inner peripheral portion of the annular convex portion of the short pipe are the end portion of the resin flexible pipe inserted in the connection port portion, the protruding portion of the retaining ring and the convex portion of the short pipe. It is useful for supporting the end portion of the resin flexible tube pressed by the inside from the inside and positioning the resin flexible tube at an appropriate position. This action is similarly exerted by the configuration described in claim 3.

Since the short pipe is made of polyethylene, a polyethylene pipe body which is generally used for piping for handling combustible gas is securely welded to the tip of the short pipe by heat welding. Can be connected. Moreover, even if the short pipe is made of polyethylene, the nut body and the connection opening into which the nut body is screwed are made of synthetic resin that is less likely to cause stress relaxation than polyethylene,
Stress relaxation is less likely to occur at the fastening portion between the nut body and the connection port, which helps prevent the pressing force against the resin flexible tube from being loosened by the retaining ring, and by extension the end of the resin flexible tube to the convex portion. It helps maintain the adhesion of the parts.

Further, since the short pipe, the connection port portion connected to the base end portion thereof, and the nut body are all made of synthetic resin, there is no risk of corrosion or rusting.

The action exerted by the configuration described in claim 1 described above is also exerted by the configuration described in claim 2. Moreover, according to the configuration described in claim 2, the bulging portion of the short pipe made of polyethylene is fitted into the concave groove provided in the tubular connection opening portion and is pressed down to form the short pipe and the connection opening portion. By connecting and, the joining strength is increased as compared with the case where the connection port is simply joined to the base end portion having no bulging portion, and the connection is surely made.

According to the third aspect of the invention, since the short pipe, the connection port portion connected to the base end portion thereof, and the nut body are all made of synthetic resin, there is a risk of corrosion or rusting. Absent.

According to the method of manufacturing a synthetic resin joint for a flexible resin pipe as set forth in claim 5, a short pipe made of a molten synthetic resin injected into a molding space around the base end portion of the short pipe set in a molding die. Since the heating action of the above-mentioned base end portion is mitigated by the high heat-resistant heat insulating material made of a polyamide-based synthetic resin, thermal deterioration of the joint portion between the base end portion of the short pipe and the connection port portion is prevented. This is unlikely to occur, and this helps prevent the pressing force against the resin flexible tube from being loosened by the retaining ring, and thus helps maintain the adhesion of the end of the resin flexible tube to the convex portion.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1, 2 and 3 show a synthetic resin joint for a flexible resin tube according to an embodiment of the invention described in claims 1 and 2.

Reference numeral 1 is a polyethylene short tube having an outer diameter of about 30 mm or less and a length of about 170 mm. Reference numeral 10 denotes a cylindrical connection port portion, and this connection port portion 10
Is formed of a polyamide-based synthetic resin or polyacetal that is less likely to cause stress relaxation than polyethylene. Nylon 66 is a typical example of the polyamide-based synthetic resin, and it is also possible to use nylon reinforced with glass fiber or the like. Polyamide-based synthetic resins and polyacetals have excellent mechanical strength, are hard, and can be cut. The connection port portion 10 is provided with a concave groove 17, and the large-diameter bulging portion 11 a provided at the base end portion 11 of the short pipe 1 is fitted into the concave groove 17 and is pressed to fit the connection port portion 10.
And the short tube 1 are connected. The connection between the base end portion 11 of the short pipe 1 and the connection port portion 10 will be described in detail when the method for manufacturing a synthetic resin joint for a resin flexible pipe according to the fifth aspect of the invention is described.

The connection port 10 has an internal thread 1 at one end thereof.
2 is formed by molding or cutting, and a stepped portion 14 having a small diameter and having a tapered guide surface 13 is formed at the terminal end of the inner screw 12 thereof.
To form a cylindrical surface.

As shown in detail in FIG. 7, in the short pipe 1, the base end portion 11 located at the rear end of the stepped portion 14 is used as an annular convex portion 15, and the convex portion 15 An annular protrusion 16 is formed on the inner peripheral portion, and a concave groove 17 is annularly formed on the end surface of the convex portion 15 (the end surface of the end tube 1). Further, the pipe body 1 can directly connect a straight pipe made of polyethylene to the tip end (not shown) by heat welding.

As shown in detail in FIG. 4, an annular protrusion 1
6, the outer peripheral surface of the taper surface 16a is a widened tapered surface 16a, and the diameter of the smallest diameter portion of the tapered surface 16a is slightly smaller than the inner peripheral diameter of the valley portion a2 of the resin flexible tube A. .
The protrusion 16 does not necessarily have to be annular,
It may be provided at a plurality of locations on the inner peripheral portion of the annular convex portion 15 so as to project in a partial arc shape or a pin shape.

Reference numeral 2 denotes a nut body, which has an external thread 21 at the tip thereof, and has an inner surface of the tip which extends outwardly and has a tapered contact portion 22.
Has been made. An outer screw 21 of the nut body 2 is screwed onto an inner screw 12 of the connection port portion 10 of the joint body 1. Here, the nut body 2 is formed of polyamide-based synthetic resin or polyacetal as described above that is less likely to cause stress relaxation than polyethylene. The nut body 2 may be made of synthetic resin reinforced with glass fiber or carbon fiber.

Reference numeral 3 denotes a retaining ring formed of a cylindrical body, which has a cutout shape as shown in FIG. 5, and an annular projecting portion 32 is provided inward at the front end of the cylindrical portion 31, The guide surface 13 of the connection port 10 is provided on the outer periphery of the overhanging portion 32.
A tapered surface 33 that slides with is formed. further,
On the outer periphery of the rear end of the cylindrical portion 31, a tapered surface 34 that slides on the contact portion 22 of the nut body 2 is formed. The retaining ring 3 has an overhang portion 32 whose inner diameter in the natural state is larger than the outer diameter of the peak portion a1 of the corrugated resin flexible tube A, and is shown in FIG. When the entire retaining ring 3 is reduced in diameter against its own elasticity so that the gap 35 of the broken circle portion is completely closed as shown in FIG. 6, the inner peripheral diameter of the overhanging portion 32 can be made of resin. The diameter is equal to or slightly smaller than the outer diameter of the valley portion a2 of the flexible tube A.

When the retaining ring 3 is set in the connection port portion 10, even if the outer diameters of the tapered surface 33 and the tapered surface 34 in the natural state of the retaining ring 3 to be set are slightly different, the connection port is The outer screw 21 of the nut body 2 is screwed to the inner screw 12 of the connection port portion 10 so that the retaining ring 3 is sandwiched and fixed between the guide surface 13 of the portion 10 and the contact portion 22 of the nut body 2. The retaining ring 3 is fixedly set so that it does not move without rattling. Therefore, when the resin flexible tube A is inserted into the connection port portion 10, the retaining ring 3 does not rattle and it becomes difficult to insert it. Even in such a set state, the retaining ring 3
The inner diameter of the overhang portion 32 is larger than the outer diameter of the mountain portion a1 of the resin flexible tube A, and the gap 35 is kept open.

When the corrugated resin flexible tube A is to be connected, the connection port portion 1 in which the retaining ring 3 is set as described above.
As shown in FIG. 1, the resin flexible tube A has a protrusion 1 at its end A1.
After 6 is fitted and its end A1 is inserted to a position where it is supported by the projection 16 from the inside, the nut body 2 screwed to the connection port 10 is screwed in the direction of the arrow X in FIG. In this case, the stopper portion 3 of the nut body 2 pushes the retaining ring 3 backward, and accordingly, the tapered surface 33 of the retaining ring 3 slides over the guide surface 13 of the connection port portion 10, so that the retaining ring 3 moves. It moves forward while reducing the diameter inward in the radial direction, and in the middle of the process, the protrusion 32 of the retaining ring 3
Engages between the ridges a1 and a2 of the resin flexible tube A and pushes the end A1 of the resin flexible tube A to move it forward.

Thus, when the end portion A1 of the resin flexible tube A is advanced, the diameter of the large diameter portion of the tapered surface 16a of the protrusion 16 is smaller than the inner diameter of the valley portion a2 of the resin flexible tube A. Moreover, when the end portion A1 of the resin flexible tube A is the valley portion a2 or the peak portion a1, the end portion A of the resin flexible tube A is
1 is pressed against the convex portion 15 of the connection port portion 10 without expanding the diameter. Then, the nut body 2 is completely screwed in (in this state, the tapered surface 33 of the retaining ring 3 exceeds the guide surface 13 and the retaining ring 3 is backed up from the outside by the cylindrical surface of the stepped portion 14. 3) and 6), when a portion of the end portion A1 of the resin flexible tube A is clamped between the protruding portion 32 of the retaining ring 3 and the convex portion 15, as shown in FIG. At the same time, it is supported from the inside by the protrusions 16,
The end A1 of the resin flexible tube A is in close contact with the taper surfaces 16a of the projections 15 and the protrusions 16 to form an airtight seal, and the end portion A1 of the resin flexible tube A which is pressed is a retaining ring. By engaging with the overhanging portion 32 of 3 in the pull-out direction, a reliable pull-out preventing action is exhibited. Particularly, since the end portion A1 of the resin flexible tube A is supported from the inside by the protrusion 16, the resin flexible tube A
Is strongly pulled in the pulling-out direction, the end portion A1 of the resin flexible tube A to be pressed is deformed and slipped through the inside of the overhanging portion 32 of the retaining ring 3 and is hardly pulled out. Very large pull-out strength is secured.

On the other hand, as described above, the end portion A of the resin flexible tube A is
1 is moving forward, taper surface 1 of protrusion 16
When the diameter of the large diameter portion 6a is larger than the inner diameter of the valley portion a2 of the resin flexible tube A, and the end portion A1 of the resin flexible tube A is the valley portion a2, the resin flexible tube The end portion A1 of the pipe A is first pressed against the tapered surface 16a of the protrusion 16, and then the tapered surface 16a is pushed up while being expanded in diameter and pressed against the convex portion 15 of the connection port portion 10 as shown in FIG. 4, for example. Then, in a state where the nut body 2 is completely screwed in, as in the case described above, a portion of the end portion A1 of the resin flexible tube A having a few ridges extends over the protruding portion 32 of the retaining ring 3 and the convex portion 14 described above.
It is supported by the protrusions 16 from the inside at the same time when it is pressed between them. Therefore, the end portion A1 of the resin flexible tube A adheres to the tapered surface 16a of the protrusion 16 with an extremely strong force, and the contact portion between the end portion A1 and the convex portion 15 and the tapered surface 16a of the protrusion 16 is more reliably airtight. Sealed. The point that the pull-out strength of the resin flexible tube A is secured is the same as described above.

As shown in FIG. 1, if a rubber ring 4 such as an O-ring is previously inserted in the groove 17 of the connection port 10, the rubber ring 4 is flexible when the nut body 2 is completely screwed. The pipe A is compressed by the pressed end A1 and comes into pressure contact with the surfaces on both sides of the concave groove 17 and seals the periphery of the above-mentioned airtightly sealed portion.

In this embodiment, the nut body 2 and the connection port portion 10 into which the nut body 2 is screwed are made of synthetic resin which is less likely to cause stress relaxation than polyethylene forming the short pipe 1, specifically nylon 66 or polyacetal. Since it is made of, stress relaxation at the fastening portion between the nut body 2 and the connection port portion 10 is unlikely to occur, which helps prevent the pressing force against the resin flexible tube A by the retaining ring 3 from loosening, As a result, the resin flexible tube A for the convex portion 15 is provided.
It helps to maintain the adhesion of the end A1 of the. Nevertheless, since the short pipe 1, the connection port portion 10 coupled to the base end portion 11 thereof, and the nut body 2 are all made of synthetic resin, there is no possibility of causing corrosion or rusting. In addition, the bulging portion 11a of the base end portion 11 of the short pipe 1 made of polyethylene and the concave groove 17 of the connection opening portion 10 are fitted and pressed together, so that the short pipe 1 and the connection opening portion 10 are joined together. The strength is increasing.

FIG. 8 shows a synthetic resin joint for a flexible resin tube according to the third embodiment of the invention. In this embodiment, the difference from the one described in FIGS. 1 to 7 is that the short pipe 1 and the connection port 10 provided at the base end 11 of the short pipe 1 are made of the same kind of synthetic resin. However, it is not necessary to connect the short pipe 1 and the connection port portion 10 together. As the synthetic resin for the short pipe 1 and the connection port portion 10, in addition to polyethylene, a polyamide-based synthetic resin, polyacetal, or the like is appropriately selected. Since other matters are the same as those described with reference to FIGS. 1 to 7, the same or corresponding parts will be denoted by the same reference numerals and detailed description thereof will be omitted.

FIG. 9 shows a synthetic resin joint for a flexible resin tube according to an embodiment of the invention described in claim 4. In this embodiment, the tubular body 1 is configured such that a synthetic resin tubular body for piping, for example, a polyethylene tubular body 200 is connected to a tip portion of the tubular body 1, and the material thereof is polyethylene. The proximal portion of the short pipe 1 is provided with a large-diameter engagement portion 18 in a bulging shape. The cylindrical connection port 10 is made of a synthetic resin that is less likely to cause stress relaxation than a short pipe, for example, a polyamide synthetic resin or polyacetal as described above. The base portion of the connection port portion 10 is externally fitted to the engagement portion 18, and the connection port portion 10 is provided with an annular engagement portion 19 protruding inward in the radial direction and the connection port portion 10.
The engaging portion 18 of the short tube 1 is held by the pressing tool 5 screwed into the base of the above.

The nut body 2 is formed of a synthetic resin that is less likely to cause stress relaxation than polyethylene such as polyamide synthetic resin or polyethylene such as polyacetal, and the retaining ring 3 that can be reduced in diameter is set in the connection port 10. The configuration and operation of the retaining ring 10 itself, the other configuration of the connection port 10 and the other configuration of the short pipe 1 are the same as those described with reference to FIGS. 1 to 7.

Also in this embodiment, since the nut body 2, the connection port portion 10 and the tube body 1 are made of synthetic resin, there is no fear of corrosion or rusting, and the connection port portion 10 or the nut body 2 is also prevented. Is made of a synthetic resin that is less likely to cause stress relaxation than polyethylene, so stress relaxation is less likely to occur at those fastening portions, which prevents the retaining ring 3 from loosening the pressing force against the resin flexible tube A. This is useful, and in turn, useful for maintaining the adhesion of the end portion A1 of the resin flexible tube A to the convex portion 15. Other operations are the same as those described with reference to FIGS. In FIG. 9, the same or corresponding parts as those in FIGS. 1 to 7 are designated by the same reference numerals.

FIG. 10 shows a form of use of the synthetic resin joint for a flexible resin tube according to the present invention. In the figure, 6 is a mechanical joint, and the mechanical joint 6 connects the short pipe 1 to which the connection port portion 10 is connected and the iron pipe 7. The resin flexible tube A is connected to the connection port 10.

Next, an embodiment of a method of manufacturing a synthetic resin joint for a flexible resin tube according to claim 5 will be described.
This method is a method of manufacturing the synthetic resin joint described in FIGS. That is, in this method, the polyethylene short tube 1 having the large-diameter bulging portion 11a provided at the base end portion 11 is preformed. The base end portion 11 of the short tube 1 including the bulging portion 11a is made of a highly heat-resistant heat insulating material 6 made of a polyamide synthetic resin or a synthetic resin reinforced with glass fiber or carbon fiber. Coated,
After that, the base end portion 11 of the short tube 1 is set in a molding die.
Next, in the molding space around the base end portion 11 of the short pipe 1, a synthetic resin which is less likely to cause stress relaxation than polyethylene synthetic resin or polyethylene such as polyacetal is injected in a molten state and the connection port 10 is injected. Mold. According to this method, the heating action of the molten synthetic resin on the base end portion 11 of the short tube 1 is such that the heat-resistant heat of polyamide-based synthetic resin or synthetic resin reinforced with glass fiber or carbon fiber is used as a material. Since it is relieved by the insulating material 6, thermal deterioration of the joint portion between the base end portion 11 of the short pipe 1 and the connection opening portion 10 is unlikely to occur, and this is due to the pressing force of the retaining ring 3 against the resin flexible pipe A. Of the resin flexible tube A and the end portion A1 of the resin flexible tube A to the convex portion 15 are maintained. As a specific example of the heat insulating material 6, a product obtained by processing an aromatic polyamide synthetic resin into a non-woven fabric, for example, Nomex under the trade name of DuPont can be preferably used.

[0039]

According to the synthetic resin joint for a flexible resin pipe according to the invention described in claim 1 or 2, since the short pipe is made of polyethylene, it is generally used for a pipe handling a combustible gas at its tip. Even though it is possible to reliably connect the polyethylene pipe body used by heat welding, the connection port and the nut body are made of synthetic resin that is less likely to cause stress relaxation than polyethylene,
Stress relaxation is unlikely to occur at those fastening parts, which shows the effect that the adhesiveness of the end of the resin flexible tube to the convex part on the short pipe side is maintained and the sealing property is maintained for a long time. Help to let. Further, since the pipe body, the connection port portion, and the nut body are all made of synthetic resin, there is no risk of corrosion or rusting.

Claim 1, Claim 2, Claim 3, and Claim 4
In the synthetic resin joint for a flexible resin tube according to any one of the inventions described above, the retaining ring has a protruding portion formed in an oval shape having a size into which a corrugated flexible resin tube can be inserted, and a nut body. Since the retaining ring moves forward while reducing the diameter by screwing in, set the retaining ring in advance at the connection port where the nut body is screwed, and insert the resin flexible tube into it. By simply screwing in the nut body, the resin flexible tube is securely connected in a state where it is retained, and the reliability and workability of the connection work are improved compared to the conventional case. In addition, the protrusion provided on the inner peripheral portion of the annular convex portion of the tubular body supports the end portion of the resin flexible tube from the inside during connection work and after connection, and positions the resin flexible tube at an appropriate position. To help you. Therefore, when connecting a resin flexible tube made of polyethylene, which is used for flammable gas piping, to a joint, even though the resin flexible tube is more easily deformed than a metal tube, There is an advantage that the pipe connection work can be performed easily and surely, and at the same time, sufficient pull-out resistance after connection can be secured.

According to the synthetic resin joint for a flexible resin tube according to the second aspect of the present invention, the connection between the connection port portion and the short pipe is strengthened.

According to the method for producing a synthetic resin joint for a flexible resin tube as set forth in claim 5, there is an effect that thermal deterioration is less likely to occur at the joint between the pipe body and the connection port.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing a first stage when a resin flexible tube is connected to a synthetic resin joint of the invention described in claim 1 or claim 2.

FIG. 2 is a partial cross-sectional view showing an intermediate stage when connecting a resin flexible tube to the synthetic resin joint of the invention described in claim 1 or 2.

FIG. 3 is a partial cross-sectional view showing a final stage when a resin flexible tube is connected to the synthetic resin joint of the invention described in claim 1 or 2.

FIG. 4 is an enlarged cross-sectional view showing a state where an end portion of a resin flexible tube is in contact with a convex portion of a tubular body.

5 is an enlarged cross-sectional view taken along the line VV of FIG.

6 is an enlarged cross-sectional view taken along line VI-VI of FIG.

FIG. 7 is an enlarged cross-sectional view illustrating a joint portion between a pipe body and a connection port portion.

FIG. 8 is a partial cross-sectional view showing a final stage when a resin flexible tube is connected to the synthetic resin joint of the invention described in claim 3.

FIG. 9 is a partial cross-sectional view of a resin flexible tube in the synthetic resin joint of the invention described in claim 4.

FIG. 10 is an explanatory diagram showing a usage pattern of a synthetic resin joint for a flexible resin tube according to the present invention.

FIG. 11 is a partial cross-sectional view showing a usage state of a conventional joint.

[Explanation of symbols]

A resin flexible tube 1 short tube 2 nut body 3 retaining ring 5 pressing tool 6 thermal insulating material 10 connection port portion 11 base end portion of short tube 11a bulging portion 13 guide surface 15 convex portion 16 protrusion 18 engaging portion 19 Engagement part 22 Contact part 31 Cylindrical part 32 Overhang part 33 Tapered surface 100 Polyethylene tube (synthetic resin tube for piping)

Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication location B29K 77:00 105: 08 (72) Inventor Ichiro Kawabata 1 day steel pipe fittings at 153 Tajime-cho, Kishiwada-shi, Osaka (72) Inventor Hideo Hirabayashi One day at 153 Tajime-cho, Kishiwada-shi, Osaka

Claims (5)

[Claims] 1. A tubular connection port made of synthetic resin, which is less likely to cause stress relaxation than the short pipe, at the base end of a polyethylene short pipe to which a synthetic resin pipe body for piping is connected at the distal end. The nut body screwed into the connection port portion in a state where the parts are joined and fitted onto the resin flexible tube inserted into the connection port portion is formed of a synthetic resin that is less likely to cause stress relaxation than the short pipe. Along with it, a retaining ring that can be reduced in diameter and is set in the connection port is provided, and the retaining ring is provided with an annular bulging portion inwardly at the front end of the cylindrical portion, and The peripheral diameter of the flexible tube is larger than the outer diameter of the resin flexible tube, and a tapered surface is formed on the outer periphery of the overhang portion, and the nut body is screwed into the connection port portion. When pushing the retaining ring, The retaining ring has a contact portion that allows the retaining ring to be reduced in diameter, and the connection port part slides on the tapered surface of the retaining ring pushed by the nut body to reduce the retaining ring radially inward. The short tube has an annular shape that abuts against the end of the resin flexible tube that is advanced by meshing with the protruding portion of the retaining ring having a reduced diameter. A synthetic resin flexible tube characterized by having a convex portion and a protrusion provided on an inner peripheral portion of the convex portion and fitted into an end portion of the resin flexible tube to support the end portion from the inside. Resin fitting. 2. A tubular connection port formed of a synthetic resin in which the bulging portion of a polyethylene short tube having a large-diameter bulging portion at the base end is less likely to cause stress relaxation than the short tube. The synthetic resin joint for a resin flexible pipe according to claim 1, wherein the short pipe and the connection port portion are joined by being fitted and compressed in the concave groove provided in the. 3. A tubular connection port made of a synthetic resin of the same kind as this short pipe is integrally formed at the base end of the short pipe made of synthetic resin to which a synthetic resin pipe for piping is connected at the tip. A nut body that is provided and that is screwed into this connection port while being externally fitted to the resin flexible tube that is inserted into this connection port is made of synthetic resin, and has a reduced diameter that is set in the connection port. The retaining ring, which is capable of retaining, is provided with an annular bulging portion inwardly at the front end of the cylindrical portion, and the inner diameter of the protruding portion is the outer diameter of the resin flexible tube. It is formed by a cylindrical body of a larger circular shape than that, and a taper surface is formed on the outer periphery of the overhanging portion, and the nut body pushes the retaining ring backward when screwed into the connection opening portion. , And has a contact part that allows the retaining ring to be reduced in diameter. The portion is provided with a tapered guide surface that slides on the tapered surface of the retaining ring that is pushed by the nut body to advance the retaining ring while radially reducing the retaining ring inward. A ring-shaped protrusion that abuts the end of the resin flexible tube that is advanced by engaging the protrusion of the diametrical retaining ring with the protrusion. A synthetic resin joint for a resin flexible pipe, characterized in that it has a projection that fits into the end of the pipe and supports the end from the inside. 4. A polyethylene pipe having a distal end to which a synthetic resin pipe body for piping is connected is provided with a large-diameter engagement portion in a bulging shape at the base end thereof, and the stress is higher than that of the short pipe. A tubular connection port made of a synthetic resin that does not easily relax is externally fitted to the engagement part, and an annular engagement part protruding inward in the radial direction provided on the connection port and the connection port The engaging portion of the short pipe is held by a pressing tool screwed into the base of the connector, and screwed into the connection port while being fitted onto the resin flexible pipe inserted into the connection port. The nut body is made of synthetic resin that is less likely to cause stress relaxation than the short pipe, and has a retaining ring that can be reduced in diameter and is set in the connection port. An annular overhang is provided inwardly, and the inner diameter of the overhang is the above resin. The nut body is formed by a cylindrical body having a larger diameter than the outer diameter of the flexible tube, and a taper surface is formed on the outer periphery of the overhang portion, and the nut body is pulled out when screwed into the connection port portion. It has a contact part that allows the retaining ring to be reduced in diameter while pushing it backwards, and the connection port part slides on the tapered surface of the retaining ring that is pushed by the nut body to make the retaining ring radius smaller. The short tube is provided with a tapered guide surface for advancing while reducing the diameter inwardly, and the short tube is an end of a resin flexible tube that is advanced by being meshed with the overhanging section of the retaining ring having a reduced diameter. A ring-shaped convex portion that comes into contact with the portion, and a projection that is provided on the inner peripheral portion of the convex portion and that fits into the end portion of the resin flexible tube and supports the end portion from the inside. Synthetic resin joint for resin flexible tube. 5. A method of manufacturing a synthetic resin joint for a flexible resin tube according to claim 2, wherein a short pipe made of polyethylene having a large-diameter bulged portion provided at a base end is set in a molding die. Before injection molding the connection port by injecting molten synthetic resin into the molding space around the base end of the short pipe, the base end of the short pipe is made of polyamide synthetic resin, glass fiber or carbon fiber. It is coated with a high heat resistant heat insulating material made of a synthetic resin reinforced by the, and then the large diameter of the proximal end of the short pipe is inserted into the groove of the connection port through the heat insulating material. A method for manufacturing a synthetic resin joint for a flexible resin tube, characterized by forming a bulged portion.