JPH02296093A - Electrical insulating tube fitting - Google Patents

Abstract

PURPOSE:To simplify manufacture and improve the measure accuracy of a screw by mixing resin powder material and reinforcing material made of insulating powder or fiber and coating the surface of the screw part of a tube fitting main body adhesively with this mixture. CONSTITUTION:Electrical insulating and thermosetting resin such as epoxy resin and phenol resin is used for resin powder material, and ceramic carbon powder, fiber, and the like are used for electrical insulating reinforcing material. These are mixed to form a fluidized bed. When a heated or primer applied tube fitting main body 1 is placed in the fluidized bed, the mixture of the resin powder material and the reinforcing material adheres to the surface of the main body 1. In case adhesion is unnecessary, the surface is neither covered nor applied with the primer. When the main body 1 is bakingly heated, a female screw part, the inner peripheral surface and the side end surface are adhesively coated with an insulating layer 2. The manufacture of this pipe fitting is relatively simple, and the female screw on the surface of the insulating layer is desirable in its measure accuracy.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a screw-type electrically insulating pipe joint.

In particular, the present invention relates to an electrically insulating pipe joint in which an electrically insulating layer is formed on the threaded portion.

[Prior Art] A conventional screw-type electrically insulating pipe joint in which an electrically insulating layer is formed on the threaded portion is disclosed, for example, in Japanese Patent Application Laid-Open No. 153091/1983, and a longitudinal cross-sectional view of this is shown in FIG. Indicated by

This electrically insulated pipe joint is a socket-type screw-in joint, and has a cylindrical metal joint body 4 with female threads on the inner circumferential surface of both ends, and a metal fitting body 4 that is threaded onto the surface of the female thread. It consists of an electrically insulating sheet-like composite material 5 made of a polymer and inorganic fibers that is bonded together. This electric shock I11
Electrically insulating sheet-like composite material 5 on the inner peripheral surface of both ends of the pipe joint
The female thread part has a standard thread diameter and shape.

On the other hand, Japanese Unexamined Patent Publication No. 153090/1983 describes a method of manufacturing an electrically insulated pipe joint as described above.

That is, the first step is to mold the female thread part of the joint body 4 to a diameter larger than the standard female thread diameter, and the second step is to mold the female thread part of the joint body 4 to a diameter larger than the standard female thread diameter. Place the insulating sheet-like composite material 5 on the female threaded portion of the joint body 4, and then place the third electrically insulating sheet-like composite material 5 on the female threaded portion so as to follow the female thread shape. A manufacturing method is described in which the composite material 5 is pressurized, and then the curable resin of the composite material 5 is finally cured and fixed.

[Problems to be Solved by the Invention] The electrically insulated pipe joint described above is characterized in that an electrically insulating sheet-like composite material is pressurized along the female thread of the joint body, and after the pressure is applied, The outer surface of the sheet composite has a standard thread shape. Here, there is a problem in that it is difficult to pressurize the sheet-like composite and process it into a standard screw shape.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrically insulating pipe joint in which the electrically insulating layer forming a standard thread shape can be formed relatively easily.

[Means for Solving the Problems] The present invention includes a metal pipe joint body that is cylindrical in shape and has a threaded portion at its end, and a surface of the threaded portion of this pipe joint body is coated and fixed. This is an electrically insulating pipe joint characterized by comprising an electrically insulating layer made of a mixture of a resin powder material and an electrically insulating powdered or fibrous reinforcing material.

[Function] The electrical insulating pipe joint of the present invention described above can be manufactured as follows, and it is not difficult to manufacture it in this way.

For example, if a heated pipe fitting body is placed in a fluidized bed in which a mixture of resin powder and reinforcing material flows, the mixture of resin powder and reinforcing material will adhere to the surrounding surface of the pipe fitting body. At this time, an electrically insulating layer may be coated to mask or cover surfaces that do not require adhesion. When the pipe joint body to which the mixture of the resin powder material and the reinforcing material is attached is baked and heated, an electrically insulating layer is coated and fixed onto the pipe joint body.

[Example] An example of the present invention is shown in a longitudinal sectional view in FIG. The electrically insulated pipe joint shown in FIG. 1 is a socket-type screw-in joint, and is connected to a pipe 3 having a thread formed on the outer peripheral surface of its end.

This electrically insulated pipe joint has a cylindrical shape with female threads formed on the inner circumferential surfaces of both ends, and the pipe joint body is made of metal, such as cast iron.
Then, the surface of the female thread of this pipe joint body 1 was coated and fixed. It consists of an electrically insulating layer 2 made of a mixture of a resin powder material, such as an epoxy resin powder material, and an electrically insulating powder reinforcing material, such as ceramic particles or powder.

The shape and dimensions of the female thread on the outer surface of the electrical insulating layer 2 are similar to those of a standard female thread.

Here, as the resin powder material, in addition to epoxy resin powder material, electrically insulating thermosetting resin such as phenol resin powder material and polyester resin powder material is used, and electrically insulating nylon powder material is also used. The size of these resin powder materials is about 10μ to 50μ.

On the other hand, electrically insulating powder reinforcing materials include electrically insulating ceramic powder reinforcing materials, electrically insulating glass, carbon powder reinforcing materials, electrically insulating ceramic, glass,
and carbon fiber reinforcement. Here, the fiber is fibrous, that is, elongated.

Next, a description will be given of coating and fixing the electrical insulating layer 2 made of a mixture of a resin powder material and a reinforcing material on the surface of the female thread of the pipe joint body l.

The resin powder material and reinforcing material as described above are mixed to form a fluidized bed thereof. This fluidized bed is made by placing the mixture on one side of a perforated plate.

It is formed when air is blown from the other side.

The pipe fitting body is inside this fluidized bed! When heated or coated with plastic miner, a mixture of resin powder and reinforcing material adheres to the surface of the pipe joint body 1. At this time, on the surface where this adhesion is unnecessary, that is, the pipe fitting body l
Do not mask, cover, or apply primer to the outer surface of the product.

Next, the mixture of resin powder material and reinforcing material is baked on the pipe fitting body l attached to the surface except for the outer circumferential surface, and when it is heated, the inner circumferential surface including the female thread part of the pipe fitting body l, An electrically insulating layer 2 is coated and fixed on the side end faces.

Here, the surface of the female threaded portion of the pipe joint body l is coated with the electrically insulating layer 2 and fixed, so the outer diameter of this female threaded portion should be increased by the thickness of the electrically insulating layer 2. . Since the female thread shape of the electrically insulating layer 2 needs to have the dimensions of a standard female thread shape, the surface may be processed into the standard female thread shape and dimensions after the electrically insulating layer 2 is coated and fixed. At this time, since the pipe joint body 1 is made of cast iron, the outer circumferential surfaces of both ends thereof may be machined, and the machined surfaces may be used as reference surfaces to machine into a standard female thread shape. Furthermore, this standard surface and processed surface can also be used as a reference surface when processing the female threaded portion of the pipe joint body 1.

In addition to forming the fluidized bed described above, in order to attach the mixture of resin powder and reinforcing material to the pipe joint body 1,
They may be applied using a static coating method. Furthermore, when forming a fluidized bed and attaching it, the pipe fitting body 1 is placed inside the fluidized bed.
There are cases where the entire pipe fitting body 1 is placed, and cases where a fluidized bed is formed only inside the pipe joint body 1.

The electrically insulating pipe joint of this embodiment described above is not difficult to manufacture and is relatively simple, and the female thread on the surface of the electrically insulating layer 2 also has the advantage of good dimensional accuracy.

The electrically insulating pipe joint described above is of the socket type, but it can also be a screw-in type electrically insulating pipe joint of the elbow, tee, or nipple having a thread at the end.

[Effects of the Invention] As explained above, the electrically insulating pipe joint of the present invention is relatively easy to manufacture without being difficult, and has the advantage of good dimensional accuracy of the screw.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of this embodiment, and FIG. 2 is a longitudinal sectional view of a conventional example. 1.4...Pipe joint body 2,5...Electric insulation layer 3...Pipe

Claims (1)

[Claims] A metal pipe joint body having a cylindrical shape and a threaded end, and a resin powder material and electrically insulating powder coated and fixed on the surface of the threaded part of the pipe joint body. Alternatively, an electrically insulating pipe joint characterized by comprising an electrically insulating layer made of an integrated material mixed with a fiber-like reinforcing material.