JPH0420366B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing an L-shaped pipe joint for preventing corrosion at the end of a pipe, and more specifically, a method for forming an anti-corrosion resin layer on the inner surface of an L-shaped pipe joint. This relates to a manufacturing method.

[Conventional technology]

In general, piping systems, such as water piping systems, use piping whose inner surfaces are treated with anticorrosive resin as part of its anticorrosion measures, and pipe joints that connect these pipings, in this case L-shaped pipes, are used. Joints that have an anticorrosive resin layer formed on their inner surfaces are also used.

By the way, in the case of this piping system, the pipe whose inner surface has been treated with an anti-corrosion resin is usually cut to a predetermined size before use, so the end face of the cut pipe is made of metal fabric that has not been anti-corrosion treated. Therefore, when connecting using an L-shaped pipe joint during piping, it becomes a problem to take anti-corrosion measures on the end face of the cut pipe.

Therefore, in the past, when this pipe end surface was connected to an L-shaped pipe joint, it was necessary to prevent it from being exposed.
The structure of No. 10483 (Figure 8) was proposed.
Here, 1 is a pipe, 2 is an anti-corrosion resin layer on the inner surface of this pipe, 3 is a cut end surface of the pipe exposed as a raw material, and 4 is screwed onto the end of the pipe 1 to connect them to each other. 7 is an anti-corrosion resin layer on the inner surface of this L-shaped pipe joint. However, it is completely unclear how to actually manufacture the structure shown in Fig. 8 to form such an anticorrosion resin layer 7 on the inner surface of the L-shaped pipe joint, and in reality, such a method is not possible. It was believed that it was impossible to form a corrosion-resistant resin layer 7.

Therefore, even after the structure shown in Fig. 8 was made public, it was still inferior to the structure shown in Fig. 8 in terms of workability, strength, and anti-corrosion performance of the end face of the cut pipe. Although inferior, various anti-corrosion L-shaped pipe joints have been provided in response to this problem. However, recently, a corrosion-resistant pipe joint having a structure similar to that shown in FIG. 8 has been provided.

As shown in Fig. 9, this similar anti-corrosion pipe joint is an L-shaped pipe joint to which the resin injection molding method has been applied. Each sleeve portion 8 is made to protrude from the inner surface 6 other than the threaded portion 5, leaving a gap 11 between the sleeve portion 5 and the same threaded portion 5, which is sufficient to receive the pipe end of the piping 1. The edible resin member 9 is formed by resin injection molding.

However, in the case shown in FIG. 9, thick portions 10 are formed in the anticorrosion resin member 9 due to undercuts during molding, which necessitates a longer molding cycle. The resin for the thick wall is wasted, and a sharp edge is formed at the ridge 10a of the branch part due to its structure, which reduces the pressure of the water flowing inside the pipe.
This results in a so-called water pressure loss, and in addition, in order to injection mold the anti-corrosion resin member 9 into the L-shaped pipe joint 4, an expensive mold is required due to its configuration, which increases the initial cost of the product. Put it away.

The present invention has been made in view of the above circumstances, and provides an L-shaped pipe for preventing corrosion at the end of piping, which can be easily and inexpensively manufactured with the configuration shown in FIG. 8, rather than the one shown in FIG. 9. The present invention attempts to provide a method for manufacturing a joint.

[Means for solving problems]

That is, the present invention has an L-shaped pipe joint in which a threaded portion is formed on the inner surface of a pair of connecting portions located at symmetrical L-shaped positions, and a sleeve portion is provided with a predetermined gap between each threaded portion. A manufacturing method for forming a resin layer for corrosion protection on the inner surface of a pipe joint, in which a mask socket having a through hole is fitted into both threaded parts of the L-shaped pipe joint, and a blow molding method is used in this state. The heated and plasticized parison is first introduced into the pipe joint through the through-hole of one mask socket, and then the end of the introduced parison is removed by a pick-up jig that is inserted from the through-hole side of the other mask socket. , and take it out through the through hole of the other mask socket. Then, compressed air is blown into this parison part to blow mold it. Then, each mask socket is removed, and the end corresponding to each connection part is properly connected. This is a method of manufacturing an L-shaped pipe joint for preventing corrosion at the end of a pipe, characterized by cutting and shaping the pipe to form a resin layer by a parison part.

〔Example〕

The following is an example of the method for manufacturing an L-shaped pipe joint for preventing corrosion at the end of a pipe according to the present invention, and FIGS.
This will be explained in detail with reference to the drawings.

Fig. 1 is a longitudinal cross-sectional view of an L-shaped pipe joint in which a corrosion-protective resin layer is formed by the method of this embodiment, and Figs. 2 to 5 are longitudinal cross-sectional views showing the steps of forming the same resin layer sequentially. be.

In these embodiments of FIGS. 1 to 5,
The same reference numerals as in the conventional example in FIGS. 8 to 9 indicate the same or corresponding parts, and the reference numerals 4a and 4
5a and 5b are threaded portions formed inside the connecting portions 4a and 4b.

However, in this embodiment method, first, as shown in FIG. The formed mask sockets 14a and 14b with flanges are fitted in advance and masked. That is, each of these mask sockets 14a, 14b serves as a mold for blow molding, which will be described below, and the thickness of the socket that covers the threaded portions 5a, 5b of each connection portion 4a, 4b is the same as that described above. It corresponds to the wall thickness of the end of the pipe 1, and forms the gap 11 described above after molding.

Next, each screw portion 5a, 5b is masked by each mask socket 14a, 14b, and the L
As shown in FIG. 3, the molded pipe joint 4 is appropriately held in a blow molding machine, and the parison 16 heated and plasticized at about 200°C is inserted into the L-shaped pipe through the through hole 15a of the one mask socket 14a. Fitting 4
After introducing the pick-up jig 1 into the inside of the mask socket 14b, the pick-up jig 1 is inserted from the through-hole 15b side of the other mask socket 14b.
7, and with this pick-up jig 17,
While holding the ends of the parison 16 introduced earlier, as shown in FIG.
The ends of the parison 16 are taken out through the through hole 15b of the other mask socket 14b at a speed synchronized with the introduction speed, and both ends of the parison 16 are placed outside of both mask sockets 14a, 14b. , the pinch bars 18, 18 are used to press down the blowing pipe 1 from one end side.
Insert 9.

Then, as shown in FIG.
9 to approximately 2 kg/cm ² to 4 kg/cm ² of compressed air is blown into the parison 16, and the parison 16 is inserted into the above-mentioned mask socket 14a,
14b, and the inner surface 6 of the L-shaped pipe joint 4, and finally, the parison 1
The resin layer 20 according to No. 6 can be blow molded.

and then each mask socket 14
a, 14b, and each connection part 4a, 4b
As shown in FIG. 1, by appropriately cutting and shaping the end portions of the resin layer 20 corresponding to the
Sleeve portions 20a, 20b are provided between the threaded portions 5a, 5b with a predetermined gap 11 therebetween, and L
On the inner surface 6 of the molded pipe joint 4, the desired resin layer 20 that is tightly adhered can be obtained.
In addition, if necessary, these inner surfaces 6 and the resin layer 2
0 can also be bonded with an adhesive or the like as appropriate.

In addition, in the above embodiment, each mask socket 14
A and 14b were used with smooth inner circumferential surfaces, but instead of this, for example, as shown in FIG. An annular groove 14'a', 14'b' may be formed therein. If such mask sockets 14'a' and 14'b' are used, by air blowing the above-mentioned thermoplasticized parison 16, the sleeve portion 20 can be formed as shown in FIG.
Annular protrusions 20a', 20 on the outer peripheral surfaces of a, 20b
b' can be easily formed, the annular protrusions 20a', 20b' and the sleeve parts 20a, 20
Due to the elasticity of the material b, it can be brought into close contact with the resin layer 2 on the inner peripheral surface of the pipe 1. Therefore, watertightness with the resin layer 2 can be more effectively achieved, and corrosion protection of the pipe cross section of the pipe 1 can be reliably avoided.

〔Effect of the invention〕

As described in detail above, according to the method of the present invention, in an L-shaped pipe joint in which an anticorrosion resin layer is formed on the inner surface, the inner surface of the pipe joint includes a sleeve portion with a gap between each threaded portion. The resin layer for
Since one parison is continuously molded using the blow molding method, it is possible to easily form a resin layer with a sleeve part in an L-shaped pipe joint with a substantially uniform thickness, and the exposed surface at the cut end of the pipe can be easily formed. In addition to preventing corrosion, the sharp edge at the L-shaped bent part is eliminated, and water pressure loss is also improved. By simply operating the pick-up jigs in conjunction with each other, a resin layer can be obtained in a short molding cycle using a conventional blow molding machine, without the need for any special equipment or expensive molds. Moreover, since there is no waste in the resin used, it can be formed at low cost, and by masking each threaded part, it is possible to reliably and easily form a gap to receive the end of the pipe. It has the following features.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an L-shaped pipe joint in which an anticorrosive resin layer is formed by a method according to an embodiment of the present invention;
2 to 5 are longitudinal sectional views sequentially showing the molding process of the same resin layer, and FIGS. 6 and 7 are longitudinal sectional views of main parts and L-shaped parts showing other embodiments of the present invention. FIG. 8 is a vertical sectional view of a pipe joint, and FIGS. 8 and 9 are longitudinal sectional views each showing an L-shaped pipe joint on which an anticorrosion resin layer is formed according to different examples of the conventional art. 1...Piping, 2...Anti-corrosion resin layer on the inner surface of the pipe,
3... Piping end face part, 4... L-shaped pipe fitting, 4a, 4
b...Connection part of L-type pipe joint, 5a, 5b...Threaded part of L-type pipe joint connection part, 6...Inner surface part of L-type pipe joint, 14a, 14b...Mask socket, 15
a, 15b... through hole of mask socket, 16...
...Parison, 17...Pickup jig, 19...
...Compressed air blowing pipe, 20...Resin layer, 20a,
20b...Sleeve portion of the resin layer.

Claims (1)

[Claims] 1 A pair of L-shaped pipe joints with threaded parts formed on the inner surface of a pair of connecting parts located in symmetrical positions, and a sleeve part with a predetermined gap between each threaded part for corrosion protection on the inner surface of the pipe joint. A manufacturing method for forming a resin layer, wherein a mask socket having a through hole is fitted into both threaded portions of the L-shaped pipe joint, and in this state, a blow molding method is used,
First, the heated and plasticized parison is introduced into the pipe joint through the through hole of one mask socket, and then the end of the introduced parison is clamped by a pick-up jig that is inserted from the through hole side of the other mask socket. At the same time, this is taken out to the outside through the through hole of the other mask socket, and then compressed air is blown into this parison part to cause blow molding.After that, each mask socket is removed, and the end corresponding to each connection part is cut and shaped as appropriate. A method for manufacturing an L-shaped pipe joint for preventing corrosion at the end of a pipe, characterized in that a resin layer is formed by a parison part.