JPH0334541Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a corrosion-resistant pipe joint whose outer peripheral surface is coated with a synthetic resin layer. In particular, it is suitable for large-diameter pipe joints of two and a half inches or more.

[Conventional technology and its problems]

Conventionally, corrosion-resistant pipe fittings were developed using the
No. 91989 is publicly known.

However, the corrosion-resistant pipe joint described in Utility Model Application Publication No. 56-91989 has the following drawbacks. That is,
Although it may be good for a pipe fitting with a relatively small nominal diameter (2 inches or less), if you look at it as a large-diameter pipe fitting of 2 and a half inches or more, it is a shape that wastes a lot of metal and synthetic resin material, so to speak. There are many
The disadvantage is that the weight is excessive, and the inner circumferential surface of the stretched covering tube extending from the end of the metal joint pipe is straight (same inner diameter) and has a lot of fat, and there is a difference in diameter from the female thread of the metal joint pipe. The problem is that a large amount of sealant is required (for large-diameter pipe fittings), and that sufficient compressive force is applied to the sealant when screwing the pipe and fitting together. It has the disadvantage that it is difficult to seal tightly.

The first purpose of the present invention is to eliminate such conventional drawbacks, and to provide a design that is particularly suitable for large diameters (2 and a half inches or more), and to provide an efficient shape for metal materials and synthetic resin materials. The object of the present invention is to provide a pipe joint that is lightweight and has sufficient strength.

Furthermore, the second objective was to reduce the excess weight of the metal material to create a lightweight, large-diameter pipe fitting, but to maintain the strength around the female thread when working with a strong external force with a torque wrench or vise. The objective is to create a pipe joint that is especially large and does not cause deformation or damage.

In addition, the third purpose was to make the synthetic resin layer thinner and less bulky to save material while increasing its resistance when strong rotational torque is applied with a torque wrench, etc., and to prevent it from falling to the ground. The goal is to maintain the strength to not break even at times.

The fourth object is to reduce the amount of sealant used, ensure reliable sealing, and allow the sealant to flow smoothly during threading work with the male threaded portion of the pipe.

[Means to solve the problem]

In order to achieve such an objective, the present invention covers the outer circumferential surface of a metal joint pipe with a synthetic resin layer, and the end of the synthetic resin layer is formed into an integral part extending beyond the end of the metal joint pipe. In a pipe joint equipped with a stretched coated cylindrical portion, the outer diameter of the end portion of the outer peripheral surface of the metal joint pipe is made larger than the remaining portion, and a low outer flange portion of a predetermined width is formed at the end portion, and A female thread is formed on the inner circumferential surface of the end of the metal joint pipe, and a bevel-wrapped portion is further formed with a portion of the synthetic resin layer to cover the lower outer flange, and the bevel-wound portion is formed with a portion of the synthetic resin layer. The outside diameter of the section is set larger than the rest of the synthetic resin layer, and the width of the beveled portion is set larger than the width of the female screw and sufficiently larger than the width of the low outer flange. And, moreover,
The outer circumferential surface of the stretched covering tube part has a stepped part with a large rounded part that is larger than the thickness dimension of the part corresponding to the low outer flange part of the honeycomb winding part, and has a stepped part with a large rounded part that has a base outer diameter of the honeycomb winding part. Furthermore, the inner circumferential surface of the stretched covering tube is formed into a tapered inner circumferential surface that gradually expands in diameter toward the tip, and the tapered inner circumference The inner diameter of the proximal end of the surface is
The diameter was set to be approximately equal to the diameter of the female screw 2 described above.

[Effect]

The metal joint pipe has a low outer flange that can sufficiently withstand large forces (when gripped with a torque wrench and when the male threaded portion of the pipe is threaded). Even if other parts are made thinner, sufficient strength can be ensured overall. Therefore, it is also possible to reduce the weight.

The beveled portion covers the lower outer flange. This makes it possible to sufficiently withstand even when a strong rotational torque is applied using a torque wrench. especially,
The width dimension of this beveled portion is set larger than that of the low outer flange portion and the female thread portion to ensure a sufficient area of the portion where the powerful rotational torque is transmitted by the torque wrench, and to reduce the surface pressure. Lower the metal joint to prevent separation from the outer surface of the pipe.

In addition, by reducing the thickness of the synthetic resin in areas other than the beveled portions, it is possible to reduce the weight and save the amount of synthetic resin material.

In addition, the outer circumferential surface of the stretched coating tube part is straight through a stepped part with a large rounded part, and on the other hand,
The inner peripheral surface has a tapered inner peripheral surface that gradually expands in diameter at the tip, so it is rational in terms of strength, and the root part -
The strength near the end of the metal joint pipe is sufficiently improved.

In addition, when connecting a pipe (synthetic resin-coated metal pipe), a sealant is inserted between the male thread of the pipe and the female thread of the pipe joint, and the sealant is inserted inside the stretched coating. The inner circumferential surface of is tapered,
In addition, since the inner diameter of the proximal end of this tapered inner circumferential surface is approximately equal to the diameter of the female thread, only a small amount of sealant is required, and excess sealant flows easily to the outside when screwing in, making it reliable. You can fill the gap between.

〔Example〕

Hereinafter, the present invention will be explained in detail based on the illustrated embodiments.

In FIG. 1, an elbow type pipe joint 1 is shown as an example, and this pipe joint 1 consists of a metal joint pipe 3 having a female thread 2 on its inner circumferential surface, and a synthetic resin layer covering its outer circumferential surface 4. 5, and a synthetic resin stretch-coated cylinder part 8 in which the end 6 of the synthetic resin layer 5 extends beyond the end 7 of the metal joint tube 3. Of course, the stretched covering tube portions 8, 8 are extended at both ends and are molded integrally with the intermediate synthetic resin layer 5.

The outer circumferential surface of the stretched coated tube part 8 is formed in a stepped shape with a stepped part 10 having a large radius R. In other words, it has a stepped shape with the tip outer diameter d set smaller than the base outer diameter D, and
For example, when the diameter of the screw 2 is 4 inches, the radius dimension of the radiused portion R is set to approximately 4 to 8 mm. Also, if the diameter of screw 2 is 6 inches, the radius dimension is approximately 6
~12mm.

Furthermore, as is clear from the figure, a low outer flange 11 with a predetermined width A is formed at the end 7 of the metal joint pipe 3, and the protruding height dimension H of the low outer flange 11 is
Set smaller than the average wall thickness Tb of the middle part of
Further, the width A is set smaller than the axial dimension of the female thread 2 - the width dimension. The synthetic resin layer 5 includes a beveled portion 12 having a width B that is sufficiently larger than the width A of the low outer flange portion 11 and an outer diameter that is the same as the outer diameter D of the base portion. That is,
A bevelled portion 12 is formed at the end portion 6 of the synthetic resin layer 5, and the outside diameter thereof is continued to the base outside diameter D of the stretched coating tube portion 8, and a large rounded portion is formed at the end thereof. It has a rounded portion R and is reduced to a small outer diameter d of the tip. That is, as is clear from the figure, the beveled portion 12 exists on the outer circumference of the screw 2. Further, assuming that the thickness dimension at the end portion 6 of the synthetic resin layer 5 - that is, the low outer flange portion 11 - is Tf, the numerical value of the rounded portion R of the stepped portion 10 is set as follows.

Tf≦R≦5×Tf For example, if Tf is 5mm, R is 5 to 25mm
If it is smaller than 5 mm, stress concentration tends to occur, and if it is larger than 25 mm, the wall thickness at the base end of the stretched coating tube 8 becomes excessively thick. Therefore, in the present invention, a radius dimension larger than Tf is referred to as a large radius R.

Note that it is also preferable to form the stepped portion 13 on the inner end side of the beveled portion 12 into a large rounded portion as shown in the imaginary line. Further, although the illustrated example shows an elbow, it is also possible to use a cheese, socket, union, etc.

In addition, FIG. 1 shows a case where a synthetic resin-coated metal pipe (pipe) 15 having a male threaded portion 14 is connected to the pipe fitting 1, and the sealant 16 is applied by expanding the diameter in the opening direction and gradually increasing the diameter toward the tip. A portion between the metal tube 15 and the stretched coating cylinder portion 8 having a tapered inner circumferential surface 17 whose diameter is expanded is filled.

[Effect of idea] The present invention has the above-mentioned significant effects.

Material is concentrated on areas that are likely to be damaged when gripped with a torque wrench, vise, etc. and rotational torque is applied - the vicinity of the end 7 of the metal joint pipe 3 and the vicinity of the end 6 of the synthetic resin layer 5. Place, reinforce,
By minimizing the other wall thicknesses, we were able to rationally save material and reduce the weight of large-diameter (2 and a half inches or more) pipe joints.

When the bevelled portion 12 is tightened with a vise, torque wrench, etc., the low outer collar portion 11 of the metal joint tube 3 effectively supports (reinforces) it from the inside, preventing strain in the inner diameter direction. It also withstands strong rotational torque.

The cross-sectional shape of the stretched coating tube 8 has a thick wall at the base portion (the end portion on the side of the metal joint pipe 3) and a gradual thinner wall toward the tip side, and the outer shape changes at a large radiused portion R that does not cause stress concentration. Even if a large-diameter, heavy main pipe joint is dropped, the stretched covering tube 8 is unlikely to be damaged. Moreover, there is almost no fat in the covering cylinder part 8.

Since the inner circumferential surface of the stretched coating tube part 8 has a tapered inner circumferential surface 17 that gradually changes, the inner circumferential surface 17 of the stretched coating tube 8 has a tapered inner circumferential surface 17 that changes gradually. Seal sealant 16
However, during this time, it is easy to fill the inside, and the surplus easily flows outside. Therefore, good sealing performance can be obtained.

The inner diameter of the proximal end of the tapered inner circumferential surface 17 is set to be approximately equal to the diameter of the female thread 2, and the distance between the tapered inner circumferential surface 17 and the male threaded portion 14 of the tube 15 is set to be approximately equal to the diameter of the female thread 2. Therefore, the amount of sealant 16 used can be reduced, and the amount of sealant 16 can be saved.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway front view showing an embodiment of the present invention. 2...Female thread, 3...Metal joint pipe, 4...Outer circumference, 5...Synthetic resin layer, 6, 7...End, 8...
Stretched coating tube part, 10...Stepped part, 11...Low outer flange part, 12...Beveled part, A...Predetermined width, D...
Base outer diameter, d...Tip outer diameter, R...Round part,
Tf...Thickness dimension.

Claims (1)

[Scope of utility model registration request] The outer peripheral surface 4 of the metal joint pipe 3 is coated with a synthetic resin layer 5, and the end portion 6 of the synthetic resin layer 5 is covered with the metal joint pipe 3.
An integral stretched covering cylinder portion 8 extending beyond the end portion 7 of the
In a pipe joint equipped with the above, the outer diameter of the end portion of the outer circumferential surface 4 of the metal joint pipe 3 is made larger than the remaining portion, and a low outer flange portion 11 with a predetermined width A is formed at the end portion, and A female thread 2 is formed on the inner circumferential surface of the end 7 of the metal joint pipe 3, and a part of the synthetic resin layer 5 is further formed on the inner circumferential surface of the end 7.
A beveled part 12 is formed to cover the low outer flange part 11, and the outer diameter of the beveled part 12 is set to the synthetic resin layer 5.
The diameter of the beveled portion 1 is larger than that of the remainder of the
2 is set to be larger than the width dimension of the female screw 2 and sufficiently larger than the width A of the low outer flange 11, and the outer circumferential surface of the stretched covering tube part 8 is The beveled portion 12 has a stepped portion 10 with a large rounded portion R having a thickness dimension Tf or more at a portion corresponding to the low outer flange portion 11 of the portion 12.
It is formed in a stepped shape with a tip outer diameter d set smaller than a base outer diameter D, and further, the stretched covering cylindrical part 8
The inner peripheral surface is formed into a tapered inner peripheral surface 17 whose diameter gradually increases toward the tip, and the inner diameter dimension of the proximal end of the tapered inner peripheral surface 17 is set to be approximately equal to the diameter of the female thread 2. A pipe joint characterized by: