JP2915506B2 - Pipe end anticorrosion pipe joint and its manufacturing method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pipe end anticorrosion pipe joint such as a drinking water pipe requiring anticorrosion properties, and relates to an adhesive for preventing a core from rotating in a joint body. The present invention relates to a pipe end anticorrosion pipe joint capable of simultaneously performing an inner coating step and a colored coating step on an outer surface for the purpose of identification, and a method of manufacturing the same.

2. Description of the Related Art Rust is mixed in tap water to generate red water, and as a cause of extremely poor tap water output, for example, water pipes and fittings themselves due to an increase in the amount of added chlorine due to deterioration of water quality. Corrosion has been noted. In order to prevent such corrosion, pipes and pipe joints in which a corrosion-resistant resin is lining-formed or injection-molded only on the inner peripheral surface or both inner and outer peripheral surfaces are commercially available.

2 and 3 show the socket-type pipe joint 1 and the cheese-type pipe joint 5 which have been subjected to the corrosion-resistant treatment. In the case of the socket shown in FIG. 2, internal threads 3 are provided on both inner peripheral sides of the joint main body 2, and a resin core 4 is provided between the internal threads 3 on both sides in the main body 2. The two pipe members to be connected are screwed into the female screw 3 from both sides of the main body 2 and are brought into close contact with the insertion portions 4a and 4b provided on both sides of the core 4.

In the case of the cheese type pipe joint 5 shown in FIGS. 3 (a) and 3 (b), the joint main body 6 has a female screw 7 on three sides, and the main body 6 has insertion parts 8a formed on three sides. A T-shaped resin core 8 is provided.

By the way, many of the joint main bodies 2 (6), including the illustrated pipe joints 1 and 5, are made of casting. Therefore, core 4
When the molten resin is injection-molded in the molding of (8), there is a problem that a slight gap is generated between the molded core 4 (8) and the main body 2 (6) due to shrinkage accompanying cooling of the molten resin.

For example, in the socket-type pipe joint 1 shown in FIG. 2, when the pipe member is screwed in a state in which a gap is generated between the core 4 and the main body 2, the core 4 and the inner peripheral surface of the main body 2 together with the pipe member. There is an inconvenience of rotating around. In the case of the cheese-type pipe joint 5 shown in FIG. 3, when the pipe member is screwed into one of the three connection ports 6B, the other connection is made as shown in FIG. At the port 6A, the core 8 is moved to one side, and at the connection port 6A, screwing of the pipe member may be difficult or impossible.

Conventionally, an adhesive is applied to a predetermined position inside the joint main body 2 (6) before injection molding. That is, when the molten resin is injection-molded after the application of the adhesive, the molten resin contracts with cooling, but no gap is generated between the molded core 4 (8) and the main body 2 (6) due to the adhesive action. Even when the pipe member is screwed, co-rotation can be prevented by the adhesive force.

On the other hand, with respect to the pipe end anticorrosion joint, an appropriate color coating is applied to the outer surface to distinguish it from other types of pipe joints.

PROBLEM TO BE SOLVED BY THE INVENTION In a conventional pipe end anticorrosion pipe joint, an internal coating step of an adhesive for bonding the core 4 (8) and an external coloring coating step for identification from the appearance are separately performed. In addition, since the application of the adhesive depends on the brush coating, the operation is complicated and the cost is increased, and the productivity cannot be improved. In addition, there is a problem that the brush coating of the adhesive causes unevenness on the applied surface, which causes a decrease in the adhesive strength of the core.

An object of the present invention is to solve the above problems and to provide a pipe end anticorrosion pipe joint capable of achieving an improvement in productivity and a method of manufacturing the same.

Means for Solving the Problems The pipe end anticorrosion pipe joint (10) according to the present invention comprises a coating agent (30).
Body (11) coated with inner and outer surfaces
And a resin core (20) injection-molded inside the joint body (11) and a coloring agent added to a hot melt adhesive, and the core (20) is attached to the inner surface of the joint body (11). A coating agent (30) for bonding and covering the inner surface and the outer surface of the joint body (11);

The method of manufacturing the pipe end anticorrosion pipe joint includes a step of preparing a coating agent (30) by adding a coloring agent to the hot melt adhesive, and a step of forming an inner surface of the joint body (11) by the coating agent (30). A coating process for coating the outer surface, and a molten resin is injected into the joint body (11) to form a core (20), and the inner surface coating agent (30) is melted by the molten resin heat at the time of injection. Bonding the molded core (20) to the joint body (11). The method may include a step of coating the inner surface and the outer surface of the joint main body (11) by the electrostatic coating method or the fluid immersion coating method using the coating agent (30).

According to the present invention, the core (20) and the joint body (11) can be firmly adhered to each other by the coating agent (30) obtained by adding a coloring agent to the hot melt adhesive, and the inside of the joint body (11) can be firmly adhered. Surface and external surfaces can be coated simultaneously. Thereby, since the outer surface of the joint body (11) can be colored and painted, it is possible to distinguish it from other types of joints.

In the method for manufacturing a pipe end anticorrosion pipe joint according to the present invention, when a molten resin is injected into the joint body (11) to form the core (20), a coating agent on the inner surface of the joint body (11) is heated by the molten resin. The core (20) molded from the molten resin is adhered to the inner surface of the joint body (11) by the hot melt adhesive contained in the coating agent (30). Therefore, due to the adhesive force of the hot melt adhesive, the gap between the core (20) and the joint body (11) is suppressed after the molten resin is cooled, and the core (20) is screwed into the pipe member when screwed. Co-rotation can be prevented.

Embodiment An embodiment of a pipe end anticorrosion pipe joint according to the present invention and a method of manufacturing the same will be described below with reference to FIG.

FIG. 1 shows a cheese-type pipe joint 10 to which the present invention is applied as an embodiment. Female screws 12 to 14 are formed in the three connection ports 11A to 11C of the joint body 11, respectively, and a T-shaped resin core 20 is provided along the internal shape of the joint body 11. Connection
The insertion part 21 is provided on each of the three sides of the core 20 corresponding to 11A to 11C.
To 23 are provided. Further, as described later, the inner surface and the outer surface of the joint main body 11 are coated and coated with the colored coating agent 30, and can be distinguished from other types of pipe joints at a glance from the appearance. The joint body 11 is, for example, a cast product made of malleable cast iron or the like.
Pretreatment such as deburring of each end face is performed. After the pre-treatment of the joint body 11, after the internal threads 12 to 14 have been machined,
The process shifts to the painting process and the core 20 forming process described below.

The pipe joint 10 is manufactured through the following steps based on the joint body 11 processed as a semi-finished product.

A step of adding a coloring agent to the hot melt adhesive to form the coating agent 30;

A coating step of coating the inner surface and the outer surface of the joint body with the coating agent 30;

Molten resin is injected into the interior of the joint body 11 to form the core 20, and the coating agent 30 on the inner surface is heated by the heat of the molten resin at the time of injection.
A step of bonding the core 20 formed by melting the above to the joint body 11.

The paint 30 is prepared by adding a coloring agent to a hot melt adhesive. As the hot melt adhesive, for example, a powder such as a polyester resin and a polyamide resin is used. As the colorant, for example, an organic pigment or the like can be used.

In the painting process, using the paint agent 30 created in,
The inner surface and the outer surface of the joint body 11 are simultaneously painted.
As a coating method, an electrostatic coating method, a fluid immersion coating method, and the like are known. After immersing the joint body 11 in an immersion tank and painting the surface,
Dry by natural cooling. By adopting the fluid immersion coating method, the thickness of the coating layer formed by application becomes uniform, the adhesive strength of the core is increased, and the reliability is improved, as compared with a conventional manufacturing method in which an adhesive is brush-coated on the inner surface.

In the core forming step, the painted joint body 11 is set in a mold, and an insert (core) for molding the core 20 is inserted into the joint body 11. A molten resin of a predetermined component is injected to form a core 20 having the shape shown in FIG. Core 20
The coating agent coated on the inner surface of the joint body 11 during molding
30 is melted by the heat of the molten resin, and the core 20 is adhered to the inner surface of the joint body 11 by the hot melt adhesive in the coating agent 30. By bonding the core 20 to the inner surface of the joint body 11, even if the injected molten resin contracts due to cooling, the generation of a gap between the core 20 and the joint body 11 is suppressed, and the The co-rotation of the core 20 at the time of screwing can be prevented.

Effects of the Invention As described above, according to the present invention, the core is adhered to the inner surface by simultaneously coating the inner surface and the outer surface of the joint body with the coating agent obtained by adding the coloring agent to the hot melt adhesive. The adhesive application step and the external coloring coating step can be performed simultaneously, and work efficiency can be significantly improved by reducing the number of steps.

[Brief description of the drawings]

FIG. 1 is a sectional view of a pipe end anticorrosion pipe joint according to the present invention, FIG. 2 is a side sectional view of a conventional socket type pipe joint, and FIG.
And (b) are a plan sectional view and a side sectional view of a conventional cheese-type pipe joint, respectively. 10 ... pipe end anticorrosion pipe fitting, 11 ... fitting body, 20 ... core,
30 …… Coating agent

Claims (3)

(57) [Claims] 1. A joint body having a coating agent coated on an inner surface and an outer surface thereof, a resin core injection-molded inside the joint body, and a hot melt adhesive containing a coloring agent added thereto. And a coating agent for adhering to the inner surface of the joint body and coating the inner and outer surfaces of the joint body. 2. A step of adding a coloring agent to the hot melt adhesive to prepare a coating agent; a coating step of coating the inner surface and the outer surface of the joint body with the coating agent; Injection molding the core, melting the coating agent on the inner surface by the heat of the molten resin at the time of injection, and bonding the molded core to the joint body. Law. 3. The method for producing a pipe end anticorrosion pipe joint according to claim 2, further comprising a step of coating the inner surface and the outer surface of the joint body with a coating agent by an electrostatic coating method or a fluid immersion coating method.