JPH0110491Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention is a connecting device for metal pipes that is used to continuously line plastic-lined metal pipes on the outside while connecting and transporting metal pipes cut to a predetermined length one after another. The purpose is to prevent damage to the inner plastic lining layer during outer plastic lining.

The outer surface of the metal tube is generally lined with plastic by extruding and applying molten plastic using a round die or T-die. In this case, the metal tubes are continuously fed into the lining device, but since the metal tubes are usually cut to an appropriate length in advance for convenience in transportation or handling, the joints of the metal tubes are As a result, the coating tends to become uneven in that area, and the adhesion of the coating often deteriorates. Therefore, in order to prevent these, conventionally the metal pipes 1, 1
The tube ends 1a, 1a of the tube were connected in advance with a connector 2 as shown in FIG. 1, and then plastic 3 was coated on the outer surface.

In recent years, the use of steel pipes with plastic exteriors, which are typical of this type of metal pipes with plastic exterior linings, has been expanded to include use in water pipes, and as a result, plastic lining on the interior surface has also become required. In this case, the inner surface is usually lined first due to work procedures, but if the inner surface is lined with plastic and the outer surface is lined with plastic by connecting the metal tubes lined with plastic on the inner surface with a conventional connector 2 as shown in FIG. Metal pipe 1,1
A problem arose in that the inner plastic layer 4 of the tube ends 1a, 1a became soft and damaged due to heating.

The inventors of the present invention have conducted various studies in order to develop a coupling device that does not have such problems, and as a result, they have developed a coupling device as illustrated in Figures 2 to 4, and have already published the contents as a utility model. Application for registration (Registration application 1989-2989)
No.). Both of these connectors include the metal tube 1,
a cap 5 having a sleeve part 6 fitted to the outer periphery of the tube ends 1a, 1a and having an opening 7 in the center; It was a combination of connecting bodies 8 having protrusions 9 for connection.
The metal tubes 1, 1 are connected without touching the inner plastic layer 4 of the metal tubes 1, 1, making it easy to attach and detach, and also to easily cut the metal tubes 1, 1 whose outer surfaces have been lined with plastic. It had the characteristic of

The present invention provides a newly developed connector with a different structure, which also does not damage the inner plastic layer 4 of the metal tubes 1, 1, is easy to attach and detach, and is capable of attaching and detaching the metal tube 1 after lining. , 1 can be easily cut off.

That is, the present invention has a cap that has one side that fits with the outer periphery of the end of the metal tube, the other side that has a protrusion that is inserted into a connecting body to be described later, and that has an opening in the center. and has an inner diameter that is approximately the same diameter as the cap and that connects with the protrusion of the cap,
The present invention relates to a connector for a metal pipe lined with plastic on the inner and outer surfaces, which is formed by combining a connector whose length is at least twice the length of the protrusion of the cap.

Hereinafter, the present invention will be described with reference to embodiments shown in the drawings.

FIG. 5 is a cross-sectional view showing a state in which the tube ends 1a, 1a of metal tubes 1, 1 are connected using a connector 10, which is an embodiment of the present invention, and the outer surfaces are lined with plastic 3. As shown in the figure, the connector 10 of this embodiment includes two caps 11, a connector 12,
It consists of a total of three members, and the tube ends 1a, 1
Caps 11, 11 are fitted into both caps a, and the caps 11, 11 are connected by a connecting body 12.

The cap 11 has a circular opening 16 formed in the center of a thick disk 14, and a tubular protrusion 13 provided at the periphery of the circular opening 16. This protruding portion 13 is a portion to be inserted into the connecting body 12, and its outer peripheral surface is tapered to facilitate insertion. The length of the protrusion 13 is sufficient as long as it does not come off during transportation, and is usually about 5 to 40 mm. On the other hand, a thin sleeve portion 15 is provided on the outer peripheral edge in the axial direction opposite to the protruding portion 13 . This sleeve portion 15 is made thin as a whole to reduce bulges at the connecting portion, so that the metal tubes 1, 1 can be smoothly transferred during lining. In addition, by forming a tapered surface on the distal end side of the outer circumferential surface 17 of the sleeve portion 15 and making the end portion 18 extremely thin, the level difference with the metal tube surface is reduced, thereby making it possible to reduce the level difference in the vicinity of the end portion 18. The outer plastic layer 3 also ensures close contact with the metal tube surface. The tapered surface of the outer circumferential surface 17 may be formed over the entire length of the sleeve portion 15, but in order to increase the strength when fitted to the tube end 1a, only about half of the distal end side of the sleeve portion 15 is tapered, and the remaining portion is tapered. should be parallel planes. The appropriate length of the sleeve portion 15 is about 5 to 20 mm.
This is because the ends of plastic-lined metal tubes are threaded for the purpose of connection, but for convenience, the outer plastic layer 3 is often removed in advance within 20 mm from the ends. This is derived from the connection function of the connector.
In other words, since the outer plastic layer 3 of the sleeve portion is removed after the lining treatment, if the width exceeds 20 mm, problems tend to occur in airtight sealing, especially when mechanical joints are used.
On the other hand, if it is less than 5 mm, the holding force of the metal tube will be insufficient and the connection function may not be fully demonstrated.
The opening 16 in the center of the cap 11 is provided to prevent the connection from coming loose due to expansion of air due to heating during lining.

The connecting body 12 has a cylindrical shape, and its inner peripheral surface 2
0 has a tapered surface so that the protrusion 13 of the cap 11 can be easily inserted. The length of this connecting body 12 needs to be at least twice the length of the protrusion 13 in order to prevent the protrusions 13, 13 of the caps 11, 11 fitted onto the tube ends 1a, 1a from coming into contact with each other. It is.

Another embodiment of the connector is shown in FIG.

The connector 10' of this example is an example in which the central connector 12 in the embodiment shown in FIG. There is a convex portion 21 on one side and a concave portion 2 on the other side.
2 is provided and the two are used by fitting them together. This example has the advantage that the metal tubes 1, 1 can be cut more easily after lining.

Appropriate materials for the connector of the present invention include metals, such as iron, copper, and aluminum, and heat-resistant plastics, such as nylon and polyester. It can be manufactured by

The method of lining the outer surface with plastic using the connector of the present invention may be the same as the conventional method, and it can be used regardless of the application method such as round die or T die. FIG. 7 shows an outline of an example of the lining method. Metal tubes 1 whose inner surfaces are lined with plastic are connected using the connector 10 of the present invention, and first heated by a heating device 30 while being continuously transferred from the left side of the drawing. Subsequently, the molten plastic 33 extruded from the plastic extruder 32 is applied by passing through a round die 31, and after being cooled by a water cooling device 34, the outer plastic layer 3 at the connecting portion is cut with a circular blade or the like. . Next, lining is performed using the coupling tool 10 shown in FIG. 5 and the coupling tool 10' shown in FIG.
Cut the outer plastic layer 3 at step 5 to make the metal tube 1,
FIG. 8 shows a cross-sectional view of 1 cut away. The connector is removed from the cut end 1a of the metal tube 1, and the outer plastic layer 3 at the part where the sleeve parts 15 were fitted is removed. The recovered connectors can be used repeatedly. Pipe end 1a, 1
FIG. 9 shows a cross-sectional view of part a with the outer plastic layer 3 removed.

The plastic that can be lined using the connector of the present invention is not particularly limited, and can be widely used for polyethylene, polypropylene, vinyl chloride, etc. Furthermore, this plastic is not limited to a single layer, but may be laminated as appropriate. Metal pipes are not limited to steel pipes, and the connector of the present invention can be widely used when lining various metal pipes with plastic. On the other hand, since the plastic lining is removed from the outer surface of the end of the metal pipe lined using the connector of the present invention, the connector of the present invention is normally distributed or used in this form. It is particularly suitable for applications in which the outer surfaces of the ends are connected by screw joints, mechanical joints, etc., for example.

In the present invention, the tube ends 1a, 1a are fixed to each other using the sleeve portion 15 of the cap 11, and the protrusions 13, 13 are connected via the connecting body 12 or 12'a and 12'b. This ensures that no part of the connector is inside the metal tube, completely preventing damage to the inner plastic layer. In addition, the role of the connector of the present invention, which is used when transporting a metal pipe in the axial direction and lining it with plastic, is mainly to prevent the pipe end from rolling. The connecting structure reliably prevents this horizontal shaking, and also facilitates attachment and detachment in the axial direction, thereby improving workability. That is, it is sufficient that the connector of the present invention can exhibit such a function, for example, the protrusion 20 and the connectors 12, 12'a, 12'b.
The shape does not matter as long as it is removably fitted in the axial direction and has almost no loosening in the radial direction. Further, the wall thicknesses of the disc 14 and the protrusion 13 may be different between the cap 11 and the connecting bodies 12, 12'a, 12'b.
2, 12'a, and 12'b have approximately the same diameter, that is, to the extent that they do not impede the transfer of the connected metal tubes 1, 1 and do not cause problems in the adhesion of the outer plastic layer 4 of the tube ends 1a, 1a. Bye. The cap 11 and the connecting bodies 12, 12'a, 12'b constituting the connecting tool are 1
As shown in the embodiments, the present invention is not limited to the members.

The coupling device of the present invention has a simple structure, can reliably attach the outer plastic layer without damaging the inner plastic layer, etc., is easy to attach and detach, and is easy to attach and detach from the metal pipe after lining. It has many advantages such as being easy to cut.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of metal tubes connected using conventional connectors and lined with plastic on the outside. In addition, Figures 2, 3, and 4 are cross-sectional views of metal tubes connected using a connector developed by the present inventors and for which a utility model registration application is being applied, with the outer surface lined with plastic. It is. Fifth
6 and 6 are cross-sectional views, respectively, of metal tubes connected using a connecting device according to an embodiment of the present invention, and the outer surfaces thereof are lined with plastic. FIG. 7 is an explanatory diagram showing an overview of an example of a method of lining the outer surface with plastic, FIG. 8 is a sectional view showing a state in which the lined metal pipe is cut away, and FIG. FIG. 3 is a cross-sectional view with the outer plastic layer removed. DESCRIPTION OF SYMBOLS 1...Metal tube, 1a...Pipe end, 2...Connector (conventional example), 3...Outer plastic layer, 4...Inner plastic layer, 10, 10'...Connector (example of the present invention), 11... Cap, 12, 12'a, 1
2'b... Connecting body, 13... Protrusion, 15... Sleeve part, 16... Opening.

Claims (1)

[Claims for Utility Model Registration] 1. One side has a protrusion that fits with the outer periphery of the tube end of a plastic-lined metal tube whose outer surface is lined with plastic, and the other side has a protrusion that is inserted into a connecting body to be described later, and a cap having an opening in the center, and an inner diameter that is approximately the same diameter as the cap and connected to the protrusion of the cap, and whose length is equal to the length of the protrusion of the cap.
A connector for metal pipes with plastic lining on the inner and outer surfaces, which is made by combining a tubular connector with a tubular connector that is more than double the size. 2. The connector according to claim 1 of the utility model registration claim, in which the connector is divided into two parts.