JPH09152074A - Manufacture of flanged pipe with resin-lined inner surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a flanged pipe having a resin- lined inner surface, by which a metallic pipe is not inflated by injected resin pressure nor deformed. SOLUTION: A metallic frame 2 is mounted on the outer periphery of a metallic pipe 1 having a flange 1c at its pipe end, and the metallic pipe 1 with the metallic frame 2 thereon is used as one molding die. The other molding die by which a cavity for forming a lining layer is formed between it and the metallic pipe is set from the inner surface of the metallic pipe 1 to the flanged surface at the pipe end, and after the lining layer is formed by the injection of a resin into the cavity, the metallic frame 2 is removed from the metallic pipe 1 to manufacture a flanged pipe having a resin-lined inner surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a flanged inner surface resin lined pipe by lining a resin from a metal pipe having a flange at a pipe end to a pipe end flange surface.

[0002]

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

As a method of manufacturing a flanged lining pipe (including a pipe joint) of this type, the following is conventionally known, for example. One is JP-A-49-9937.
No. 0 publication. This is because the resin pipe is inserted into the flanged steel pipe, the end of the resin pipe is projected from the steel pipe by a predetermined amount, and the cone-shaped jig is inserted into the protruding portion of the resin pipe while it is heated to rotate the resin pipe. After the pipe end surface is formed into a trumpet shape, the flared portion of the trumpet shape is reheated by the pressing plate and brought into close contact with the steel pipe flange portion.

The other one is disclosed in JP-A-54-2938.
This is disclosed in Japanese Patent Publication No. This is because the resin pipe is inserted into the flanged steel pipe and the end portion is projected from the steel pipe by a predetermined amount, and in that state, the heating liquid is passed through the resin pipe to soften it, and then the heating liquid is pressurized to end the resin pipe. The resin flange portion is brought into close contact with the steel pipe flange portion by subjecting the portion to expansion molding to a diameter not less than the outer diameter of the steel pipe flange surface.

In addition to these, for example, Japanese Patent Publication No. 4-
There is one described in Japanese Patent No. 19015. This is because the resin pipes are respectively inserted into the main pipe portion and the branch pipe portion of the branch pipe and expanded to temporarily bond them to each inner surface, and then both resin pipes are heated and softened while being pressurized from the inside with a predetermined pressure. After that, both resin parts are welded.

However, in the methods described in the above-mentioned JP-A-49-99370 and JP-A-54-29382,
It is unavoidable that residual stress is generated when manufacturing the resin part that is in close contact with the flange part by thermal processing.Therefore, while the thermal expansion and contraction due to temperature fluctuations are repeated after piping, the resin part is affected by the residual stress. It may peel off. There is also a problem that it takes time to form and finish the resin flange portion.

On the other hand, in the method described in Japanese Patent Publication No. 4-19015, expansion molding of resin pipes respectively inserted into the main pipe portion and the branch pipe portion, molding of the flange portion, welding of both resin pipes and finishing are performed. As described above, there is a problem in that the number of steps is large and the work time is accordingly long.

Therefore, in order to solve the above-mentioned problems, the present applicant uses a metal pipe having a flange at the pipe end as one of the molding dies, and for this metal pipe, from the inner surface to the pipe end flange surface. A method for forming a lining layer by setting another mold for forming a cavity for forming a lining layer with the metal tube and injecting a resin into the cavity is proposed (JP-A-7-16869).
Reference).

According to this method, it is possible to mold a lining layer that does not peel or crack due to temperature change or the like after piping so that the resin is present without interruption from the inner surface to the pipe end flange surface.

[0010]

In this method, a metal pipe having a flange at the pipe end is used as one of the molding dies. At the time of injection molding, the inner wall of the metal pipe is a resin injected into the cavity. The pressure of the injection resin is such a high pressure as to reach 300 to 500 kgf / cm ² , for example.

On the other hand, the metal tube has an outer diameter of 34 mm,
25 mm diameter with wall thickness of 4.7 mm (20 mm diameter of branch pipe)
From steel pipes with a small diameter like cheese, the outer diameter is 216.3
Various steel pipes are used up to a steel pipe having a large diameter such as cheese having the same diameter of 200 mm and a nominal diameter of 200 mm having a thickness of 8.8 mm.

By the way, the strain εθ of the steel pipe is expressed by the formula εθ =
It is represented by (pD / 2Et) × (1-ν / 2) (wherein p
Is the resin pressure, E is the Young's modulus, ν is the Poisson's ratio, D is the outer diameter of the steel pipe, t is the wall thickness of the steel pipe), and the ratio D / t of the outer diameter of the steel pipe to the wall thickness is proportional to the strain, While the D / t of cheese with the nominal diameter of 20 mm is 7.2, the nominal diameter of 2 with
The 00 mm cheese has a D / t of 24.6, which is 3.4 times more flexible than the former cheese, and when a steel pipe having a large diameter is used, the injection resin pressure is 300 to 500 kgf /.
If it becomes cm ² , the steel pipe may expand beyond the yield stress of the steel pipe, and the diameter may expand, for example, about 1 to 5 mm, and it may not be possible to obtain a flanged lining pipe (including a pipe joint) of a predetermined size.

In order to prevent the metal tube from swelling, it is conceivable to lower the injection resin pressure or the injection speed, but in this case, the resin is not sufficiently filled in the cavity, which is a so-called short shot. There is a problem of becoming. Further, it is conceivable to eliminate the short shot by increasing the resin temperature to improve the fluidity of the resin, but if the resin temperature is excessively increased, the resin is decomposed and the resin lining layer is deteriorated.

The present invention solves such a problem, and when a metal pipe is used as a molding die, the metal pipe does not swell due to the injection resin pressure, and an inner surface resin-lined pipe with a flange without deformation is manufactured. The purpose is to do.

[0015]

A method of manufacturing an inner surface resin lining pipe with a flange according to the present invention uses a metal pipe having a flange at a pipe end as one of the molding dies, and the inner surface of the metal pipe is To the pipe end flange surface, set the other mold that forms a cavity for forming the lining layer with the metal pipe, and inject resin into the cavity to form the lining layer. Inner surface resin lining with flange A method of manufacturing a pipe, comprising mounting a metal frame body on an outer periphery of the metal pipe to reinforce the metal pipe, and injection-molding a resin into the cavity to form a lining layer, and then forming the metal frame body. Is detached from the metal tube.

Steel is usually used as the material of the metal tube and the material of the metallic frame, but other metals such as cast metal and stainless steel may be used. The resin used as the lining layer is not particularly limited as long as it can be injection-molded, and examples thereof include vinyl chloride resin, chlorinated vinyl chloride resin, polyethylene, polybutene, and polyvinylidene fluoride (PVD).
Examples of the resin include F) and polyphenylene sulfide (PPS).

In manufacturing, an adhesive is usually used from the inner surface of the metal pipe to the flange surface of each pipe end.
The present invention is also applicable to loose linings that do not use such adhesives. If you use glue,
Usually, a hot melt adhesive is used, but a solvent adhesive such as a rubber adhesive can also be used.

The other mold is preferably one in which a flange mold attached to the flange and an inner rod mold inserted into the pipe joint body are separable.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a cheese manufacturing method as an example of a method for manufacturing a flanged inner surface lining pipe joint according to the present invention.

First, the main pipe portion 11 has a length of 250 mm, and the branch pipe portion 12 has a height of 70 mm, which is 50 A (outer diameter 60.5 m).
m, wall thickness 5.3 mm) cheese flanged steel pipe 1 of the same diameter is heated to 180 ° C., and its inner surface and each flange surface 1
A powder of polyester adhesive was sprayed onto 3 to form an adhesive layer, and a metal frame body 2 having a thickness of 5 mm was attached to the outer circumference of the flanged steel pipe 1.

The metal frame 2 is, as shown in FIG.
Two semi-cylindrical bodies 2 having projecting edges 2b, 2b formed on both edges and having an inner peripheral surface that abuts on the outer peripheral surface of the flanged steel pipe 1.
a, 2a. In addition, 2c, 2c ... Are bolt insertion holes, and 2d are notches for insertion of the branch pipe portion 1b of the steel pipe 1. The semi-cylindrical bodies 2a, 2a were fitted on the outer circumference of the flanged steel pipe 1, and the projecting edges 2b, 2b were fastened together by bolts and nuts (not shown) to be mounted on the flanged steel pipe 1.

The metal frame 2 is not limited to the one shown in FIG. For example, as shown in FIG. 4, the semi-cylindrical bodies 2a, 2a
One of the projecting edges may be hinge-joint 2e so as to be rotatable so that the semi-cylindrical bodies 2a, 2a can be opened and closed.

Next, the flanged steel pipe 1 fitted with the metal frame 2 was used as one molding die, to which an injection molding die 10 was set as shown in FIG.

This injection mold 10 comprises first to third flange molds 11 to 13 forming a cavity C ₂ between the flanges 1c of the steel pipe 1 and these flange molds 11 to 13.
And the _first to third inner surface rod molds 14 to 16 which are respectively inserted through the main pipe portion 11 and the branch pipe portion 12 and form a cavity C ₁ between them.

Of these, a spool 16b for injecting resin to reach the runner 16a is formed on the third inner surface rod die 16, and the spool 16b and the runner 16a are used to insert the resin into the cavities C ₁ and C ₂ . Resin is to be injected.

Further, the first and second inner surface rod molds 14, 15
Is divided into two and is connected by a fastening rod 17 in a state where their tips are butted, and the tip of the third inner surface rod die 16 is provided at a V-shaped notch 10a formed at the butted portion. It is designed to be fitted.

Further, the first to third flange molds 11 to 13
Are provided with recesses 11a to 13a into which the flanges 1c of the steel pipes 1 are fitted with each other with substantially no clearance. Recess 11
The difference between the inner diameter of a to 13a and the outer diameter of the flange 1c is 0.5.
mm.

Assembling of this injection molding die 10 and assembling to an injection molding machine (not shown) are performed by the following <1> to <<.
It went in the order of 8>. <1> Flange 1c on the main pipe side of the steel pipe with flange 1
To the recesses 12a, 13 of the second and third flange molds 1c, 1c.
After fitting and positioning with a, bolt 18 ... 1
The second and third flange molds 12 and 13 are temporarily set on the flanges 1c and 1c by 8.

<2> These flange molds 12 and 13 are inserted into the main pipe portion 1 through the first and second inner surface rod molds 14 and 15, and a fastening rod 17 having a first knock pin 19 set at a predetermined portion is temporarily set. To do.

<3> First and second inner surface rod molds 14, 1
With the second knock pins 20, 20 set in the notch 10 of 5, the third inner rod mold 16 is fitted and connected to each other.

<4> The third inner surface rod die 16 is provided with the branch pipe portion 1
The first flange mold 11 on the b side is fitted to the first flange mold 1
After the flange 1c of the branch pipe portion 1b is fitted into the concave portion 11a provided in 1 to position the first flange mold 11, this is completely set.

<5> Tighten the fastening rod 17 and set it completely. <6> Tighten each bolt 18 to completely set the second and third flange molds 12 and 13.

<7> The injection mold 10 thus assembled is set on the mounting plate 21. <8> After the spacer 22 is screwed into the screw portion 16c formed in the third inner surface rod mold 16 so that the nozzle touch force of the injection molding machine is not transmitted to the first and second inner surface rod molds 14 and 15, The locate ring 23 is set and attached in that state to the injection molding machine.

In the above case, the clearance between the flange molds 11 to 13 and the inner rod molds 14 to 16 is set to about 0.08 mm. The cavities C ₁ and C ₂ were adjusted so that the resin portion (lining layer) after lining had a thickness of 2 mm.

The vinyl chloride resin is injected into the cavities C ₁ and C ₂ of the injection mold 10 thus assembled 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). Molded.

Thereafter, the injection mold 10 is opened, and the inner rod molds 14 to 16 and the metal frame body 2 are detached from the steel pipe 1 in a procedure almost reverse to the above-mentioned assembly procedure, and as shown in FIG. The resin lining layer 5 was satisfactorily formed from the inner surface of the steel pipe 1 to the respective flange surfaces of the pipe ends, and the bulge-free cheese 6 in which the change in the outer diameter of the steel pipe 1 was 0.1 mm or less was obtained.
A flanged inner surface resin lined pipe joint was manufactured in the same manner as above except that the metal frame body 2 was not used, and the outer diameter of the steel pipe was expanded by about 3 mm.

That is, according to the method of the present invention, the steel pipe 1
Since the pipe wall of the steel pipe 1 is reinforced by the metal frame body 2 when assembled as the injection mold 10, the pipe wall of the steel pipe 1 does not swell even by a large resin pressure during resin injection, It is not necessary to set the injection pressure to a low level or to set the resin temperature to an unnecessarily high level, and injection molding can be performed under appropriate molding conditions.

Moreover, the obtained resin lining layer 5 is
Since it is obtained by injection molding, it is formed without stress strain. Therefore, after piping, peeling or cracking does not occur due to temperature changes or the like.

In the illustrated injection molding die 10, the flange 31 is formed in the recesses 11a to 13a of the flange dies 11 to 13.
~ 33 to be fitted, so the flange type 11 ~
Injection molding with 13 positioning,
At the time of resin injection, even if a force is applied to the inner surface rod molds 14 to 16 inserted into the metal pipe of the other mold in a direction deviating from the pipe axis, the flanges 31 to 31 fitted to the positioning recesses 11a to 13a The outer peripheral surface of 33 is the concave portions 11a to 13a.
The position of the mold is not displaced by being received by the inner peripheral surface of the.

The method for manufacturing the flanged inner surface resin lining pipe according to the present invention is not limited to the above. For example, in the above method, the flange type and the inner rod type are separable, but they may be integrated. When the resin lining layer is formed from the inner surface of the straight pipe to the pipe end flange surface, it is not necessary to divide the inner surface rod mold as described above.

[0041]

As described above, in the method for manufacturing a flanged inner surface resin lining pipe according to the present invention, since the metal pipe is reinforced by the metal frame body, a large resin pressure is applied when the resin is injected into the cavity. Does not cause the metal tube to swell. Therefore, the lining layer can be always formed from the inner surface of the metal tube of a predetermined size to the tube end flange surface.

Of course, by injection molding, the resin lining layer can be extremely easily formed in one step from the inner surface of the metal tube to the tube end flange surface, and only the gate cut need be performed in the finishing step. It is possible to realize a very simple manufacturing method of a flanged inner surface resin lined pipe joint.

Further, even in the case of manufacturing the branch joint, it is not necessary to weld the resin pipe as in the conventional case, so that the man-hours can be greatly reduced and the reliability of the quality can be improved.
Moreover, since the lining layer is formed by injection molding, peeling or cracking does not occur due to temperature changes or the like after piping.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention and is a vertical cross-sectional view showing a state in which a steel pipe with a flange is set in an injection molding die.

FIG. 2 is a longitudinal sectional view showing a flanged inner surface resin lined pipe joint (cheese) obtained by the injection molding die of FIG.

FIG. 3 is a perspective view showing an example of a metal frame body used in the present invention.

FIG. 4 is a side view showing another example of the metal frame body.

[Explanation of symbols]

1 Metal Pipe with Flange (Steel Pipe with Flange) 1a Main Pipe Section 1b Branch Pipe Section 1c Flange Section 2 Metal Frame 2a Half Split Cylindrical Body 2b Projected Edge 2c Bolt Insertion Hole 5 Lining Layer 6 Flange Inner Surface Resin Lining Pipe Joint ( Cheese) 10 Injection mold 1b Pipe end flange face 2b Pipe end flange face 11a Recess 12a Recess 13a Recess C ₁ Cavity C ₂ Cavity

Claims (1)

[Claims] 1. A metal pipe having a flange at a pipe end is used as one mold, and a cavity for forming a lining layer is formed between the metal pipe and the metal pipe from the inner surface to the pipe end flange surface. A method for manufacturing an inner resin lining pipe with a flange, in which the other molding die for forming a resin is set, and a resin is injected into the cavity to form a lining layer, wherein a metal frame body is attached to the outer periphery of the metal pipe. Then, the metal pipe is reinforced, a resin is injected into the cavity to form a lining layer, and then the metal frame body is detached from the metal pipe. .