JPS5935326B2 - Manufacturing method for reinforced plastic pipe fittings - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a pipe joint made of reinforced plastic, and more particularly, to a method for manufacturing a pipe joint made of reinforced plastic, and more particularly, to reduce stress concentration occurring in a flow path changing portion of a pipe joint that changes and/or divides the flow direction of a fluid. The present invention relates to an inexpensive manufacturing method for pipe joints that can be manufactured in as little as possible.

Changing and/or dividing the flow direction in a pipeline is often carried out depending on the purpose of the piping and the actual situation at the piping site, and does not apply to steel pipes, cast iron pipes, or synthetic resin pipes. Reinforced plastic pipes (hereinafter referred to as FRP pipes), which are attracting attention, are no exception.

FIG. 1 is a conceptual diagram showing an example of changing the flow direction of a conduit, in which a bent pipe 2 is arranged at an appropriate position in a conduit consisting of a straight pipe 1. ,22.50,
In addition to various joints such as 11.250, it is widely known that joints other than curved pipes, such as branch pipes such as Y-shaped pipes and T-shaped pipes, are also used. By the way, in the pipe line as shown in FIG. 1, for example, the fluid flows in the direction of the arrow, but when it comes to the curved pipe 2, the flow direction is forcibly changed. At this time, not only the laminar flow tendency in the straight pipe 1 is disturbed, but also the strong fluid pressure directly affects the pipe wall of the curved pipe 2, and the thrust force and buried flow due to the expansion and contraction of the straight pipe 1 due to temperature changes. The bending moment due to the unbalanced load at the bending portions 2a and 2b of the bent pipe 2
have a major impact on Therefore, a considerably large stress concentration occurs in the bent portions 2a and 2b, and it is conceivable that the bent pipe 2 may be damaged. Therefore, it is desirable to minimize the bend angle at the bend or to increase the curvature of the bend as much as possible, but as a practical matter, it is impossible to install pipes using only pipe fittings with small bend angles. Therefore, it is considered to be a very advantageous method to make the bent portions 2a and 2b not in a bent shape but in a rounded shape having a relatively large curvature. As a method of manufacturing such a bent pipe joint, for example, a method as shown in FIG. 2 has been considered. The core metals used in this method include a straight pipe mold 13 for forming the straight pipe-shaped insertion part 3, and a bent pipe mold for forming the bent part 4 (outer bent part 2a and inner bent part 2b) of the main body. A combination of a mold 14 and a socket mold 15 for forming the straight tubular large diameter socket part 5 is used. To manufacture a bent pipe joint using this cored metal, first each mold 13
, 14, and 15 are combined as shown in FIG. 2 to form a core metal, and after the outer periphery of the core metal is covered with a tube material and hardened, demolding is performed. As for the demolding procedure, first the rods 6 and 7 operate to demold the straight pipe mold 13 and the socket mold 15 in the direction of the straight arrow, and then the arm 8 rotates to release the bent pipe mold 14.
is removed from the mold in the direction of the curved arrow. This device is connected to, for example, an injection mold, and has an extremely useful effect when manufacturing synthetic resin pipe joints, but the device is quite complex and often breaks down even with the slightest amount of dirt, so This is not a very desirable device for manufacturing pipe joints. In other words, methods for manufacturing FRP pipe joints include, for example, the filament winding method and the spray-up method. ) is coated on the core metal, so it is difficult to avoid scattering of the resin liquid during the manufacturing process and adhesion to nearby mechanical equipment, and as shown in Figure 2, the equipment requires delicate operation. It should be said that it is not suitable for manufacturing FRP pipe joints. Therefore, an apparatus as shown in FIG. 3, for example, can be considered as an apparatus that does not require complicated operations such as rotational drawing of a mold.

With this device, it is expected that a core metal can be easily obtained by joining the straight pipe molds 8 and 9, and that the bent portions 2a and 2b can also be formed. and 9
Since the portion ' corresponds to an undercut when the mold is pulled out S, the molds 8 and 9 cannot actually be pulled out. Therefore, with the apparatus shown in Fig. 3, the bent portion 2a can be formed, but the bent portion 2b cannot be formed, and at most, the bending portion 2b cannot be formed, and at best, it is necessary to add a reinforcing material to the concerned portion or increase the coating thickness of the FRP material. Only countermeasures can be taken, and it is hard to say that it is a fundamental solution. The present invention has been made with attention to such circumstances, and its purpose is to provide a flow path changing section in the bent pipe joint or branch pipe joint that changes and/or divides the flow direction of the fluid. The object of the present invention is to provide a method for manufacturing a pipe joint extremely simply and inexpensively, which can reduce stress concentration as much as possible.

The manufacturing method according to the present invention that has achieved the above object includes coating a reinforcing plastic material on a core metal obtained by joining at least two or more mold members to change the flow direction of fluid and/or In the method of manufacturing a split FRP pipe joint, the step of assembling one core bar by removably joining at least two mold members, a joining angle of at least less than 180 degrees at the joining part of the mold members. A step of attaching a soft material or an elastic material to the outer periphery of the cored metal joining part, a step of coating the FRP material on the cored metal and curing or solidifying it, a step of separating and removing the mold member, a step of the soft material or the elastic material. The gist lies in the combination of the steps of separating and removing the elastic material from the inner circumferential wall of the pipe joint.

That is, a deformable soft material or an elastic material is attached in advance to at least one part of the core metal connection part showing a connection angle smaller than 180 degrees, which corresponds to the bent portion 2b, and after the core metal is removed, the The main feature is that the soft material or elastic material is removed from the inner circumferential wall of the pipe joint, and there are no restrictions on the structure of the mold members, the method of joining, the method of covering the FRP material, etc.

In addition, the soft material and elastic material attached to the joint portion are FR
Since it acts as a part of the core metal when covering the P material and gives a gentle curvature to the joint, it is desirable that it has a certain degree of mechanical strength and thermal stability.
However, in addition to common soft to hard rubbers and plastics, a wide variety of soft and elastic materials could be used, such as putty, clay, mortar, and crescent-shaped elastic metal pieces. The configuration and effects of the present invention will be explained in more detail below based on the drawings which are examples, but the following description is merely to describe typical examples and does not limit the present invention.

FIG. 4 is a schematic sectional view showing an example of manufacturing a bent pipe joint, in which bottomed cylindrical straight pipe molds 10 and 11 are fastened with bolts and nuts 12 at their opposing bottom surfaces.

It is usually best to provide the bolts/nuts 12 at about three locations on the opposing surfaces, but considering the workability when the operator inserts his/her hand to attach/detach, it is preferable to provide them on the side closer to the curved portion 2b. preferable. Reference numeral 16 is a soft or elastic material such as putty, clay, rubber, etc., and is attached to the outer periphery of the bent abdomen 17 to which the straight pipe molds 10 and 11 are combined.

After the core metal is formed in this way, for example, glass fiber impregnated with a thermosetting resin is wound, but in order to finish the end face of the socket part and the end face of the insertion part of the molded pipe joint beautifully, it is necessary to
Step portions 18 as shown at the base of the straight pipe molds 10 and 11
It is desirable to provide 19 and 19. Once the tube material has been coated in this manner, it is hardened or solidified by appropriate means such as heat treatment, and finally the core metal is demolded.
In order to perform the demolding operation smoothly, it is extremely preferable to apply a mold release treatment (for example, application of a mold release agent) to the outer periphery of the core metal and the outer periphery of the putty 16 in advance. When demolding the core metal, first the bolt/nut 12 is removed, then the rods 20 and 21 are retracted in the direction of the arrow, and the straight pipe molds 10 and 11 are separated and demolded. At this time, it is a matter of course that the outer periphery of the molded pipe fitting 2 should be gripped and fixed by appropriate means. When the molds 8 and 9 in FIG. 3 are pulled out, the parts that became the undercut parts 8' and 9' are replaced with separate putty 16 in the example of FIG. It remains attached to the inner wall of 2b. Therefore, the straight pipe molds 10 and 11 are removed without any resistance. When the molds 10 and 11 are removed in this manner, the putty 16 is finally removed, and the pipe joint 2 having a gentle curvature over the entire circumference is obtained. putty 1
6 may be discarded, but of course it can also be reused.
If mortar or putty is used, it may be hardened after the pipe joint is formed, but it is also possible to remove it by making it fall off. The above is an example of manufacturing a single-layer FRP pipe joint, but a multi-layer FRP pipe joint can also be manufactured in the following manner.

That is, after assembling a mold and winding resin-impregnated fibers to form an inner layer, the mold is housed in an outer mold of a split mold, with or without reinforcing bars arranged in the circumferential and axial directions on the outer periphery. Fill the gap between the inner layer and the outer mold with commonly used mortar (resin mortar, resin concrete, etc.) and harden. Next, the outer mold is divided and removed, and an outer layer is formed according to the same procedure as for forming the inner layer. Finally, by performing the same demolding operation as described above, an FRP pipe joint with extremely high strength can be obtained. FIG. 5 is a diagram showing the appearance of the mold used for the molding shown in FIG. 4, and putty 16 is attached to the outer periphery of the bent abdomen of molds 10 and 11 joined together.

As is clear from this figure, it is understood that even a metal piece 16' formed into a crescent shape in advance as shown in Fig. 6 can be applied to the present invention as long as it can be elastically deformed. It will be. FIG. 7 is a sectional view showing a core metal that can be used when the present invention is applied to the manufacture of branch pipes, in which a hollow straight pipe mold 22 and a solid straight pipe mold 23 can be freely attached and detached using bolts and nuts 12. At the same time, putty 16 is attached to the outer periphery of the joint.

Therefore, by carrying out the same procedure as shown in FIG. 4, a branch pipe joint having a branch portion with a gentle curvature can be obtained. The above-mentioned embodiments show cases in which the present invention is applied to some pipe joints, and can be applied to the manufacture of various branch pipes including those having larger bending angles and T-shaped pipes.
It goes without saying that the method of the present invention is not only applicable to the production of FRP pipe joints, but also to the production of synthetic resin pipes and clay pipes. Since the present invention is configured as described above, rounded portions having a gentle curvature can be formed extremely easily and inexpensively on the inner and outer walls of a bent pipe joint or a branch pipe joint.

Therefore, FRP pipe joints can now be applied to FRP pipe lines where iron pipe joints were commonly used for joints.
It is now possible to widely enjoy the inherent advantages of FRP pipes, such as corrosion resistance and light weight.

[Brief explanation of the drawing]

The drawings are examples for explaining the present invention. Fig. 1 is a conceptual diagram of a bent pipe, Fig. 2 is a schematic sectional view of a possible arrangement for manufacturing a bent pipe joint, and Fig. 3 is an example of an undesirable device. A schematic sectional view, FIG. 4 is a sectional view of a mold showing one embodiment, FIG. 5 is a side view of the mold, FIG. 6 is a perspective view showing a metal piece as a putty substitute, and FIG. It is a sectional view showing a mold in the case of application. 1... Straight pipe, 2... Bent pipe fitting, 8,
9, 10, 11, 22, 23...Mold for straight pipe,
16...Pate.

Claims (1)

[Claims] 1. A method for manufacturing a reinforced plastic pipe joint that changes and/or divides the flow direction of fluid by coating a reinforced plastic material on a core bar obtained by joining at least two or more mold members. A step of assembling one core metal by removably connecting the above mold members, a soft material or an elastic material is used on the outer periphery of the core metal joint part that exhibits a joint angle of at least less than 180 degrees at the joint part of the mold members. a step of covering the core with a reinforced plastic material and curing or solidifying it, a step of separating and removing the mold member, and a step of separating and removing the soft material or elastic material from the inner circumferential wall of the pipe joint. A manufacturing method for reinforced plastic pipe fittings characterized by the following characteristics: