JP3204805B2 - Lining pipe joint with flange and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flanged lining pipe joint formed by forming a resin lining layer from an inner surface of a metal pipe having a flange at a pipe end to a pipe end flange surface, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Generally, in a flanged lining pipe joint, it is necessary to form a lining layer so that resin is present without interruption from the inner surface to the pipe end flange surface from the viewpoint of preventing corrosion of a metal pipe. Further, after the piping, it is required that the lining layer does not peel off or crack due to a temperature change or the like.

[0003] As a method for producing this kind of flanged lining pipe joint (or lining pipe), conventionally,
For example, the following are known. One is disclosed in JP-A-49-99370. This is done by inserting a resin pipe into a flanged steel pipe, projecting its end by a predetermined amount from the steel pipe, and rotating the cone-shaped jig into the protruding part of the resin pipe in a heated state to rotate the resin pipe. After the pipe end face is formed in a trumpet shape, the flange turn-back portion formed in the trumpet shape is brought into close contact with the steel pipe flange portion while being reheated by the pressing plate.

Another one is disclosed in Japanese Patent Application Laid-Open No. 54-2938.
No. 2 discloses this. This is done by inserting a resin pipe into a flanged steel pipe, projecting its end from the steel pipe by a predetermined amount, passing a heating liquid through the resin pipe in that state, and softening the heating liquid. The resin flange portion is brought into close contact with the steel pipe flange portion by expanding and molding the portion to a diameter larger than the outer diameter of the steel pipe flange surface.

Further, in addition to these, for example,
There is a method of manufacturing a socket for a composite pipe as described in JP-89763A. This is to provide an injection hole in the center of the metal tube, insert a pair of cylindrical dies into the metal tube, and inject the liquid resin material from the injection hole in a state in which the ends of the metal tubes are abutted with each other. After curing, the above-mentioned middle mold is removed.

[0006]

However, Japanese Patent Application Laid-Open No.
In the method described in Japanese Patent Application Laid-Open No. 9-99370 and Japanese Patent Application Laid-Open No. 54-29382, it is inevitable that a residual stress is generated when a resin portion closely adhered to a flange portion is produced by thermal processing. While the thermal expansion and contraction due to the change are repeated, there is a possibility that the resin portion is peeled off or a crack is generated in the resin portion due to the influence of the residual stress. In addition, there is a problem that the number of steps is large, such as forming a resin lining layer on the inner surface of the metal tube, forming a resin flange portion, and finishing, so that much work time is required.

On the other hand, the method described in the above-mentioned Japanese Patent Application Laid-Open No. 49-97763 has a structure in which a liquid resin is poured into a metal pipe through an injection hole formed in the metal pipe. Cannot be applied. Therefore, when applying this method to injection molding, a holding mold for holding the socket during molding, and a mold for fitting a nozzle tip of an injection molding machine are used as auxiliary molds in addition to the medium mold. Required separately. Further, when a pipe joint with a flange is to be manufactured by this method, the overall shape becomes more complicated and the size becomes larger than that of the above-mentioned socket, so that there is a problem that the cost of the auxiliary type as described above increases. In addition, the flanged metal tube used as a material has a variation in the length dimension due to manufacturing, so it is necessary to be able to form a resin lining layer even with a somewhat irregular-sized product. It becomes more complicated (and therefore expensive).

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has been described as a flanged lining pipe joint in which a resin lining layer is formed from an inner surface of a flanged metal pipe to a pipe end flange surface. It is an object of the present invention to provide a flanged lining pipe joint which is less likely to cause peeling of a lining layer, breakage of a corner portion, etc.

Further, in order to obtain such a pipe joint, the resin lining layer can be easily formed without using an expensive auxiliary mold, and the length dimension, the thickness dimension of the resin lining layer, etc. It is an object of the present invention to provide a method for manufacturing a flanged lining pipe joint having a relatively large degree of freedom with respect to the above.

[0010]

To achieve the above object, a first invention of the present application is to provide a flanged lining pipe joint in which a resin lining layer is formed from an inner surface of a metal pipe having a flange at a pipe end to a pipe end flange surface. Wherein a short pipe portion with an internal thread is provided on a wall portion of the metal pipe to allow communication between the inside and the outside of the metal pipe.

The second invention of the present application is directed to a method suitable for producing the flanged lining pipe joint according to the first invention, wherein the metal pipe provided with the short pipe section with the inner thread is used as one of the molds. Then, after setting the other mold for forming a cavity for forming a lining layer between the metal pipe and the metal pipe from the inner surface to the pipe end flange surface, the metal pipe is set on the short pipe section with the inner thread. The tip of the nozzle of the injection molding machine is screw-fitted and set, and in this state, the resin is injected into the cavity through the short pipe portion, so that the resin is applied from the inner surface of the metal tube to the tube end flange surface. It is characterized by lining.

Here, a steel pipe is usually used as the metal pipe with a flange, but another metal pipe such as a casting or stainless steel may be used. Further, as a method of attaching or forming a short pipe portion with an internal thread to this kind of metal pipe, there is a method as shown in FIGS. 7 to 9, for example.

FIG. 7 shows a metal pipe 51 having a hole 51c extending from an outer surface 51b to an inner surface 51a.
FIG. 8 shows a method for attaching a short pipe (generally called a nipple) 52 with an internal thread 52a to 1c by welding, and FIG. 8 shows a case where a hole 61c is made in a metal pipe 61, and a screw 61c 'is made in the hole 61c.
And a short tube (generally referred to as a male-female adapter) 6 having an inner screw 62a and an outer screw 62b in the screw 61c '
FIG. 9 shows a method of screwing the metal pipe 2 into a flanged metal pipe 7 having a short pipe section 72 with an internal thread 72a from the beginning.
1 is shown.

On the other hand, as the resin of the lining material, for example, vinyl chloride resin, chlorinated vinyl chloride resin, polyethylene, polybutene, polyvinylidene fluoride (PVD)
F), injection-moldable resin such as polyphenylene sulfide (PPS).

Further, an adhesive is usually used for lining the resin from the inner surface of the metal pipe constituting the pipe joint to the pipe end flange surface, but the present invention is also applied to a loose lining which does not use such an adhesive. Applicable.
When using an adhesive, a hot-melt adhesive is usually used, but a solvent-based adhesive such as a rubber adhesive can also be used.

[0016]

According to the method of manufacturing a flanged lining pipe joint of the present invention, a metal pipe with a flange provided with a short pipe section with an internal thread is used as one molding die, and the metal pipe and a set therefor are set. A resin lining layer is formed from the inner surface of the metal tube to the tube end flange surface by injecting a resin from the short tube portion with the inner thread into a cavity formed between the other formed mold and the cavity. be able to. Therefore, the inner resin lining step and the flange forming step, which were conventionally performed separately, can be easily performed in one step.

In addition, since the resin is injection-molded through a short pipe portion having an internal thread provided on the metal pipe, a spool portion and a runner portion are not required, so that the amount of wasted resin is reduced correspondingly. In addition, since the flow of the resin is improved during molding, it is possible to mold even a resin having a relatively high viscosity, and it is also possible to mold a thin product.

Furthermore, injection molding can be performed only by setting the other mold on the metal tube with a flange and screwing the tip of the nozzle of the injection molding machine into the short tube portion with the internal thread. Since a holding die for pipes and a die for fitting a sloppy tip of an injection molding machine are not required, it is not necessary to manufacture such an auxiliary die, so that it can be manufactured at a lower cost.

In the flanged lining pipe joint manufactured by the method of the present invention, a resin lining layer is formed from the inner surface of the metal pipe to the pipe end flange surface. Since it is formed by injection molding instead of thermal processing, even if there is a temperature change after piping, peeling, breakage of corners, etc. are less likely to occur.

In addition, since the pipe joint has the above-described short pipe section with an internal thread used as a resin injection port at the time of molding, the resin section in the short pipe section may be perforated as necessary, so that the post-pipe can be formed. In, the short pipe portion can be used as a mounting portion for instruments such as a thermometer and a pressure gauge.

[0021]

Embodiments of the present invention will be described below. [First Embodiment] This embodiment relates to a case where cheese is manufactured.

As shown in FIG. 1, the length of the main pipe 1 ₁ 2
50 mm, branch pipe part 1 ₂ of height 70mm of 50A (outside diameter 60.5 mm) equal in diameter branch pipe part 1 ₂ 180 ° opposite 25A socket (with inner thread with the internal thread 2a on the side short pipe cheese Part 2) is heated to 180 ° C. by welding a flanged steel pipe 1 to which an adhesive layer (not shown) is sprayed on the inner surface 1a and each flange surface 1b by spraying a polyester-based adhesive powder. After formation, this flanged steel pipe 1
In order to injection-mold a resin from the inner surface 1a of the steel pipe 1 to each pipe end flange surface 1b, each
Were fastened with bolts 4, respectively, and the inner surface rod molds 5 were fitted to the bolts 4, and their tip portions were set to abut each other.

At this time, each flange mold 3 and inner rod mold 5
Was set to a clearance fit of about 0.08 mm. The thickness of the cavity C formed between these molds and the steel pipe 1, that is, the portion that becomes the resin portion 6 after molding was 2 mm.

Further, the inner surface-rod type main pipe 1 ₁ side 5 (5
_1, 5 ₁₎ while fastening with the fastening rod 7, the branch pipe portion 1 ₂ side of the inner surface rod type 5 (5 ₂₎ are main portion-side inner surface rod type 5 _1,
5 ₁ V-shaped cut formed in the abutting portion away portion 5a
Were fitted using knock pins 8, 8, and were set by pressing with a pressing plate 9.

The combined mold set in this manner was set at the tip of an injection molding machine nozzle having a screw structure to be fitted to the inner screw 2a of the 25A socket 2. As shown in an enlarged manner in FIG. 2, this set is provided on the inner screw 2a of the 25A socket 2 of the steel pipe 1 by using an injection molding machine nozzle 10a.
Was carried out by screwing the tip 10a. And
As shown in FIG. 3, vinyl chloride resin was injected into the cavity C formed in the combination mold using an injection molding machine having an injection temperature of 190 ° C. and a gauge pressure of 50 kgf / cm ² (source pressure of 750 kgf / cm ² ). The resin lining layer 6 was formed by injection molding.

[0026] Thus, as shown in FIG. 4, as flanged lining pipe fittings, the resin lining layer 6 is satisfactorily formed from the inner surface 1a of the flanged steel pipe 1 toward the tube end flange surface 1b and the branch pipe portion 1 ₂ cheese 1 with opposite sides of the main pipe portion 1 ₁ of the inner threaded socket 2 at the center and
1 was obtained. [Second Embodiment] This embodiment relates to the case of manufacturing a straight pipe.

As shown in FIG. 5, 25
A nipple (short tube portion with internal thread 22a) 22 attached to a 100A flanged steel pipe (outer diameter: 114.3)
(mm, length: 300 mm) An adhesive layer (not shown) is formed on the inner surface 21a and each flange surface 21b in the same manner as in the first embodiment, and then each flange surface 2 is formed.
1b, each flange type 23, 2
3 and two inner rod types 25, 2
5 is inserted into the steel pipe 21, and in this state, the inner rod 2 is pressed by the holding plate 29 and the bolt 30.
5, 25 was pressed down so as not to move.

Next, using the mold thus combined,
Injection molding was performed in the same manner as in the first embodiment. As a result, as shown in FIG. 6, as a flanged lining pipe joint, a resin lining layer 26 is formed satisfactorily from the inner surface 21a of the flanged steel pipe 21 to the two pipe end flange faces 21b, 21b, and a nipple is formed at the center of the pipe wall. 22
Was obtained.

As a final treatment of the nipple 22 (the socket 2 in the first embodiment), a plug (a plug with a screw) is generally screwed into the nipple 22 as described above. In addition, in the case of so-called loose lining, which performs lining without forming an adhesive layer on the surface to be lined, the nipple is not treated, and a hole for extracting gas permeating the resin lining layer, that is, It can be used as a vent hole.

Further, when a thermometer or a pressure gauge is provided after the piping, the resin layer in the nipple is perforated so that this portion can be used as a nipple for mounting the thermometer or the pressure gauge.

[0031]

As described above, according to the present invention, since a metal tube with a flange having a short pipe portion with an internal thread is used, a pipe end flange can be formed from the inner surface of the metal tube without using an expensive auxiliary type. The resin lining layer can be formed over the surface by an injection molding method. This makes it possible to manufacture a flanged lining pipe joint that is inexpensive and has a relatively large degree of freedom in dimension.

Since the use of the short pipe portion with the inner thread as a resin injection hole eliminates the need for providing a spool portion or a runner portion, particularly when a large-diameter or long pipe joint is manufactured, the spool portion is required. In addition to eliminating waste caused by the resin remaining in the section and the runner section, there is no resistance section (particularly the gate section) against the flow of the resin, so that molding can be facilitated accordingly.

Further, the above-mentioned short tube portion with an internal thread can be used as a mounting hole for a measuring device such as a thermometer by piercing a resin portion inside the short tube portion as necessary.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of the present invention, and is a longitudinal sectional view showing a state in which a molding die is set in a flanged steel pipe (metal pipe) and a resin is injection-molded in a cavity.

FIG. 2 is an enlarged cross-sectional view showing a state in which a nozzle tip of an injection molding machine is screwed into a socket (a short pipe portion with an internal thread) in the embodiment.

FIG. 3 is an enlarged cross-sectional view showing a state after injection molding of a peripheral portion of the socket.

FIG. 4 is a longitudinal sectional view showing the cheese (a lining pipe joint with a flange) obtained in the first embodiment.

FIG. 5 is a longitudinal sectional view showing a second embodiment of the present invention, in which a molding die is set on a flanged steel pipe (metal pipe) and a resin is injection-molded in a cavity.

FIG. 6 is a longitudinal sectional view showing a straight pipe (a lining pipe fitting with a flange) obtained in the second embodiment.

FIG. 7 is an explanatory view showing an example of a method of attaching or forming a short pipe portion with an inner thread to a metal pipe with a flange in the present invention, and showing a method by welding.

FIG. 8 is a view showing another example of a method of attaching a short tube portion having an inner thread, and showing a method of screwing in the same.

FIG. 9 is a view showing still another example of a method of attaching a short pipe part having an internal thread, and showing a method of integrally forming the metal pipe with a casting.

[Explanation of symbols]

1, 21, 51, 61, 71: Metal tube with flange 1a, 21a, 51a: Inner surface of metal tube 1b, 21b: Tube end flange surface 2, 22, 52, 62, 72 ... Threaded short tube part (2 ... socket, 22 ... nipple) 2a, 22a, 52a, 62a, 72a ... inner screw 3, 5, 23, 25 ... the other mold (3, 23) ... Flange type, 5,25 ... Inner rod type) 6,26 ... Resin lining layer 11,31 ... Flanged lining pipe joint (11 ... Cheese, 31 ... Straight pipe) 10: Nozzle of injection molding machine 10a: Nozzle tip

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F16L 58/02

Claims (2)

(57) [Claims] 1. A flanged lining pipe joint formed by forming a resin lining layer from an inner surface of a metal pipe having a flange at a pipe end to a pipe end flange surface, wherein the metal pipe has a wall portion inside the metal pipe, A lining pipe joint with a flange, wherein a short pipe section with an internal thread for communicating with the outside is provided. 2. The method for manufacturing a flanged lining pipe joint according to claim 1, wherein the metal pipe provided with the short pipe section with the inner thread is used as one forming die, and the metal pipe is used for the metal pipe. On the other hand, after setting the other mold that forms a cavity for forming a lining layer between the metal pipe and the inner pipe from the inner surface to the pipe end flange surface, the nozzle tip of the injection molding machine is inserted into the short pipe section with the inner thread. It is characterized in that the resin is lined from the inner surface of the metal tube to the tube end flange surface by injection molding the resin into the cavity through the short tube portion in this state by setting the portion by screw fitting. Of manufacturing lining pipe fittings with flanges.