JP3047442B2 - Composite joint and manufacturing method thereof - Google Patents

Description

The present invention relates to a composite joint and a method for producing the same. More specifically, the present invention relates to a composite joint having a resin part integrally formed by injection molding and a method for manufacturing the same.

[Prior Art] The present inventor has developed a composite joint composed of metal and resin and connecting a metal pipe and a resin pipe, and described in Japanese Utility Model Laid-Open No. 2-6898. FIG. 5 is a side view showing a partial cross section thereof. The composite joint includes a metal fitting 20 having a pipe thread for connecting a metal pipe on one side, and a resin socket 21 for connecting a resin pipe. These two parts are integrally formed and joined when the socket 21 is formed. However, simply by joining the metal and the resin, the degree of joining is weak and the sealing property at the joining surface is inferior. Therefore, a seal material 22 is mounted between the two. The seal material 22 is arranged in the groove of the metal piece 20 before molding the socket 21, and a contact surface pressure is applied by the pressure of the resin at the time of molding the socket 21, thereby improving the sealing property. Have been.

In addition, since the joint between the hardware 20 and the socket 21 is weak, a through-hole is provided in the projection 23 of the metal, and a bridging portion of the socket is provided in the through-hole.
24 are formed so that the hardware 20 and the socket 21 are mutually locked.

In the figure, 25 is a pipe screw, 30 is a metal pipe, and 31 is a resin pipe.

[Problems to be Solved by the Invention] The sealing property of the above-mentioned conventional composite joint is such that a sealing material disposed in a metal groove is pressed by a molten resin discharging force when a resin socket is formed. This is done by increasing the contact pressure of the metal material. However, the composite joint has the following improvements.

First, regarding the sealability of the composite joint, if the dimension of the groove and the dimension of the seal material do not have an appropriate relationship with each other, a sufficient contact surface pressure cannot be applied to the seal material. That is, when the molten resin is press-fitted, if the side surface of the groove provided in the metal object and the seal material are not in pressure contact with each other, the resin penetrates from there and the space in the groove is filled with the resin,
Since the contact surface pressure between the seal material and the hardware is not sufficiently ensured, the composite joint is inferior in seal performance. Therefore, dimensional accuracy is required at the time of processing each member, which causes an increase in cost.

Also, even if the relationship between the groove size and the seal material size is appropriate, the entire surface of the seal material on the socket side is in contact with the resin. Has a shape that cannot be deformed. For this reason, the sealability of the composite joint is
Only the contact pressure of the material itself (the contact pressure in that form)
If the internal pressure rises above a certain limit,
The sealing property is impaired. Therefore, there is no problem in using it in a normal piping system, but when it is used in a piping system in which a high pressure such as a water hammer acts, there is a concern that the sealability may be impaired.

Furthermore, when molding the socket, it is necessary to keep pressing the seal material until the press-fitted resin is sufficiently cooled and solidified, during which time the mold cannot be removed, and the production efficiency of the composite joint is poor. .

SUMMARY OF THE INVENTION The present invention provides a composite joint which can reliably obtain a sufficient sealability and can withstand a large external force regardless of the arrangement conditions of the seal material and the use conditions of the composite joint. An object of the present invention is to provide a method for manufacturing a joint.

[Means and Actions for Solving the Problems] In order to achieve the above object, the composite joint of the present invention has a first portion formed of a thermoplastic resin and a second portion formed of a material different from the thermoplastic resin. The first part is integrally formed by injection molding with the second part formed in advance, and the interface between the first part and the second part At least one sealing material for ensuring sealing properties is provided, and a resin piece that is fusible with the thermoplastic resin forming the first portion is provided between the first portion and the sealing material. ing. Further, in addition to the above structure, one or more annular projections and through holes are provided on a surface of the second portion in contact with the first portion, and the first portion fills the through holes. You can also have a structure that is. And the composite joint of this invention is manufactured as follows. A composite joint composed of a first portion formed of a thermoplastic resin and a second portion formed of a material different from the thermoplastic resin, the first joint is formed on the second portion formed in advance. When manufacturing the part by integral molding by injection molding, at least one sealing material on the surface of the second part to ensure the sealing property at the interface between the first part and the second part After the provision, a resin piece fusible with the thermoplastic resin forming the first portion is provided on the sealing material, and injection molding is performed. The sealability of the composite joint of the present invention is as follows.
It is secured as follows: That is, the sealing material provided at the interface between the first portion and the second portion is sealed by being pressed by a resin piece covering the sealing material during injection molding. This sealing material is mechanically pressed, and when an internal pressure is applied, the pressure further increases the contact pressure.
Since a so-called self-sealing action is performed, the space between the second portion and the resin piece is sufficiently sealed, and can withstand a high pressure. Further, since the resin piece and the first portion are directly fused between the resin piece and the first portion without passing through the second portion, the sealing property is sufficient. As described above, since two portions between the resin piece and the first and second portions are securely sealed, the sealing performance of the entire composite joint is ensured. The annular projection provided on the second portion serves to lock the second portion and the first portion together. Since this environmental projection is formed over the entire circumference of the second portion, it withstands a large tensile force. Further, since the first portion fills the through hole of the second portion, both are locked more firmly and can withstand even if a twisting force acts. In the method for manufacturing a composite joint according to the present invention, before injection molding the first portion, the sealing material is pressed during the injection molding of the resin piece on the second portion provided with the sealing material, that is, the injection is performed. After molding, it is set so as to be located between the first portion and the sealing material, and the first portion is injection-molded as it is. At this time, when the solution resin is press-fitted, the surface of the resin piece is melted by contact with the molten resin, and is fused and integrated with the first portion to be molded. Therefore, the space between the resin piece and the first portion is completely sealed, and the resin piece is fixed in a state where the sealing material is pressed. Is also maintained. In addition, the mold after forming the first portion can be removed at the time when the surface of the resin piece and the first portion are fused, so that a short time after resin injection is short.

Embodiment FIG. 1 is a cross-sectional view showing one embodiment of the composite joint of the present invention, and FIG. 2 is a cross-sectional view of a hardware as a second part constituting the composite joint of FIG. FIG. 3 shows another embodiment of the composite joint according to the present invention.
(B), (c), and (d) show examples of application of a resin short tube and a sealing material, which are resin pieces.

In FIG. 2, one of the metal parts is a metal pipe connecting part provided with a male pipe thread 3 and the other is a joint part 4 with a socket. The metal joint 4 is provided with a plurality of through-holes 5 in a direction intersecting the connection direction of the composite joint, and is further provided with an annular protrusion 6 on the outer edge side of the end. The shape and the number of protrusions of the outer edge annular protrusion may be arbitrarily selected. The inside of the metal joint 4 has an inner diameter larger than that of the metal pipe connecting portion, and annular grooves 7 and 8 are provided in the abutting portion and the inner peripheral surface, respectively. However, it is not always necessary to provide two grooves, but it is desirable to provide a plurality of grooves in order to prevent leakage of resin due to press-fitting of molten resin during socket molding. In addition, in this figure, the connection part of the metal pipe has a connection structure using a male screw,
A structure provided with a female screw may be used.

In FIG. 1, this composite joint is formed by integrally molding a metal fitting 1 and a resin socket 2 shown in FIG. 2 by injection molding. Socket protrusions 9 are formed in the plurality of through holes provided in the metal 1, and the metal 1 and the socket 2 are mutually locked together with the metal protrusion 6.

A resin short tube 10 made of a thermoplastic resin of the same type as the socket 2 and having an outer diameter slightly smaller than the inner diameter of the joint 4 is fitted inside the metal joint 4. The resin short tube 10 protrudes from the metal joint 4 by an appropriate length 1 (normally, it may be about 1/4 of the length L of the resin short tube).
Annular seal members 11 and 12 are arranged in grooves provided in the metal fitting 1, and the seal members 11 and 12 are pressed by a short tube 10 made of resin. In particular, the seal material 11 seals between one of the resin short pipes 10 and the hardware 1. The contact portions 13 and 14 of the resin short tube 10 and the socket 2 are joined by fusion. In the contact portion 13, the socket 2 and the resin short tube 10 are joined over the entire circumference, so that the other portion of the resin short tube 10 and the socket 2 are sealed, and the metal The joint 4 is surrounded by the socket 2 and a short tube 10 made of resin. In this way, at both ends of the resin short pipe 10, which is a joint portion of the composite joint, the sealing property is reliably ensured.

FIGS. 3 (a) and 3 (b) show an embodiment in which the shape of the resin short tube 10 is changed in the embodiment shown in FIG. FIG. 3 (a) shows the short resin tube 10 formed in an L-shape. For this reason, since the fusion | melting area with the socket 2 is large and the reliable joining of the resin is enabled, the socket part which forms the through-hole provided in the metal fitting 1 is formed with a solid material of resin. And the metal 1 are more firmly joined. Further, FIG. 3 (b) shows an example in which the resin short tube 10 is used merely for fixing the seal material 11. Therefore, the cross-sectional shape of the resin short tube 10 is not particularly limited to a square.

Next, a method for manufacturing the composite joint of the present invention will be described. FIGS. 4 (a), (b), (c) and (d) are illustrations of a method of manufacturing the composite joint shown in FIG. 1 of the present invention.

First, as shown in FIG. 4 (a), a metal part 1 having the structure shown in FIG. 2 is prepared, and annular seal members 11 and 12 made of synthetic rubber are provided in grooves provided on the inner surface of the metal part 1. Installing.

Next, as shown in FIG. 4 (b), a resin short tube 10 is fitted into the joint 4 of the hardware. The resin short tube 10 is a molded product of a thermoplastic resin such as polyethylene or polybutene. The resin type is the same as that of the socket 2. Also, resin short tube
The length 10 is such that the length can protrude from the metal joint 4.

FIG. 4 (c) shows a mold for molding a socket, and a space (a casting portion) in the shape of a socket is formed by setting the mold at a joint of metal parts.

Then, as shown in FIG. 3D, the mold 15 is pressed against the joint of the metal piece 1 to press the seal materials 11 and 12 through the short pipe 10 made of resin. The mold is held, and the molten thermoplastic resin 16 is press-fitted in this state. At this time,
The sealing material 12 prevents the molten resin 16 from entering the place where the sealing material 11 is arranged. Also, the portion of the resin short tube 10 in contact with the molten resin 16, that is, the protruding portion or the surface portion where the through hole of the metal piece 1 is located is melted by the latent heat of the molten resin 16 and, after cooling and solidifying, is joined to the socket 2. And become one. Further, the molten resin 16 is also filled in the through-hole of the hardware 1, and the projection of the socket 2 is formed. Further, if there is a gap between the hardware 1 and the short pipe 10 made of resin,
Filled with 16 further strengthens the joint of the composite joint.

At the stage where the molten resin 16 has solidified and the socket 2 has been formed, the mold 15 and the inner mold 17 are removed to obtain a composite joint made of resin and metal.

In the obtained composite joint, since the projecting portion of the resin short tube 10 and the socket 2 are thermally fused, the sealing materials 11 and 12 pressed at the time of molding the socket 2 remain in the pressed state. The sealability is maintained.

[Effects of the Invention] Since the present invention is configured as described above, sufficient sealing properties can be reliably obtained regardless of the arrangement conditions of the sealing material and the usage conditions of the composite joint, and large external forces can be endured. A composite joint and an efficient manufacturing method thereof can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an embodiment of the composite joint of the present invention, FIG. 2 is a cross-sectional view of metal fittings constituting the composite joint of FIG.
FIG. 4 is a partial sectional view showing one embodiment of the composite joint of the present invention. FIG. 4 is an explanatory view of a method for manufacturing the composite joint of the present invention.
The figure is a side view showing a partial cross section of a conventional composite joint made of resin and metal. 1 ... hardware, 2 ... socket, 3 ... male screw for pipe, 4 ...
... Junction with socket, 5 ... Through hole, 6 ... Circular projection, 7,8 ... Circular groove, 9 ... Protrusion of socket, 10 ...
Resin short tube, 11, 12 ... annular seal material, 13, 14 ... resin short tube and socket contact part, 15 ... mold, 16 ... molten resin, 17 ... inner mold.

Claims (3)

(57) [Claims] A first portion formed of a thermoplastic resin and a second portion formed of a material different from the thermoplastic resin, wherein the second portion formed in advance is formed of the second portion. The first portion is a composite joint integrally formed by injection molding, and at least one sealing material for ensuring sealing properties is provided at an interface between the first portion and the second portion, and A composite joint, wherein a resin piece fusible with a thermoplastic resin forming the first portion is provided between a first portion and the sealing material. 2. A method according to claim 1, wherein at least one annular projection and a through hole are provided on a surface of said second portion in contact with said first portion, and said first portion fills said through hole. 2. The composite joint according to item 1, wherein 3. A composite joint comprising a first portion formed of a thermoplastic resin and a second portion formed of a material different from the thermoplastic resin, wherein the composite joint is formed in advance by the second portion. When the first portion is integrally molded by injection molding and manufactured, a seal for ensuring a sealing property at an interface between the first portion and the second portion on a surface of the second portion. A method of manufacturing a composite joint, comprising: providing at least one material; and providing a resin piece that can be fused to the thermoplastic resin forming the first portion on the sealing material and injection molding.